I don't know how much of a problem this buff/debuff change will be for PvE vs. PvP, but I think the bigger problem will be 10 man vs. 25 man raids. Blizzard's goal appears to be to make it possible to get all meaningful buffs and debuffs with a relatively small number of classes/specs, say 8-10. The question then is what to do with a class like rogues that justify their raids spots on personal dps rather than buffs.

One option is to make them do more dps fully raid buffed than other dps classes. This encourages a raid to stack rogues after getting the necessary buffers/debuffers in a 25 man raid. The alternative would be to make them do similar dps to other dps classes fully raid buffed. While this would work for 25 man raids rogues are now punished in 10 mans, because the core buffers/debuffers take all the spots and do the same dps. The only way to make them balanced for both levels of raiding, as far as I can see, is to give them raid utility and axe the idea of a class that survives on pure dps.

Yes, that is the obvious solution, and hopefully what happens. And why shouldn't it be.
The pure dps classes as we knew them are dead. I'm not sure if they will be missed, that remains to be seen I guess.
(at least mages have had a long time to learn living with it :P)

You know, if they do fix PvE vs PvP weapons/itemization, you won't really be able to stack 15 X class, since they won't have readily available top grade weapons, and gear differences might make "best dps class" lagging behind. I don't really expect we'll see S2 Sword > all t5 weapons(before buff) again and as such, you won't be competitive DPS wise with just your arena gear. Or they might stick with S4 level ranking requirement, that'd limit availability of those just as well. Same with T5+ quality crafted gear.
That's of course ignoring boss mechanics penalizing melee/ranged/caster/healer/whatever stacking. While World First guilds will have 10 alts ready to step in at any time, that's just mere handful of people and balancing around them is pretty much impossible anyway.

Blizzard has already mentioned the possibility of giving rogues more raid utility via buffs:
WoW Forums -> Raid stacking in Wrath of the Lich King

Specifically the following:

Just did a quick optimisation from that list (buffs, debuffs, mana battery). The optimal raid core, i.e. the raid that has one of every buff, debuff and mana battery role seem to be 10 people:

1 x Feral Druid (melee crit, bleed, melee slow, atk power debuff, armor debuff 2, druid stats)
1 x Balance Druid (spell crit, spell hit, melee hit debuff)
1 x Discipline Priest (increase spell power, spirit buff, damage reduction, stamina buff)
1 x Retribution Paladin (dmg %, crit strike, haste, mana battery, blessing of sanctuary)
1 x Protection Paladin (blessing of kings)
1 x Enhance Shaman (spell haste, attack buff 2, agi & str)
1 x Unholy Deathknight (melee haste, spell damage add)
1 x Frost Mage (int, frost crit)
1 x Warlock (curse of tongues)
1 x Arm/Fury Warrior (physical debuff, health buff, armor debuff 1, attack buff 1, healing debuff)

*** edit: 4th iteration, as I get some stacking issues pointed to me - quick optimisation wasn't good enough - ***

Who exactly is healing that raid?

The other 15 would be healer/more dps/tank

It's a raid core, not a full raid. There's only 1 main healer, although you could argue that the prot paladin can probably help as well with the enhance shaman. So, a 10-man will have to make choices.

If you have 25 people, then you have lots more room, of course, and you're no longer obliged to take those 10 core specialisations. But, for example, if you remove the balance druid, then you have to bring a shadow priest, an ele shaman and a hunter to replace him.

*** just edited the post to add the debuff/buffs that each class brings ***

Out of curiosity, what would be the worst case scenario? Meaning how many people maximum would you need to get all the buffs?

Why are there 2 affliction locks in that core instead of zero? The moonkin has CoR, CoE equivalents while the disc priest & mage cover fel intellect. The only classes that bring unique buffs/debuffs according to the blue post are Mages (scorch/WC), Druids (MotW), Paladins (BoK), Priests (Fort) & Shaman (Wrath of air, Blust).

There are a whole bunch of other things they didn't mention, either. For example, will Blessing of Wisdom and Mana Spring Totem stack? Will Mana Tide stack with Replenish (the new mana battery buff)? Will Heroism stack with Swift Retribution/Imp. Moonkin? I'm sure there's a lot more.

I don't believe that the one Enhance Shaman can provide both the melle and spell haste buffs simultaneously, as they're both on the same totem element (air) and the buffs are not conducive to the type of twisting mechanics we've seen in the past.

My bad. I had two curses, but my spreadsheet mixed some curses. Yes, you need only one warlock in practice. I'll edit the original post. But the shaman totem stacking adds another guy, so we're still at 10. There's also a war-only ability that I missed.

If you wanted the core 10 man, the spell haste shaman could easily be resto, so there's another healer. If you need a 3rd, you can drop the mage (lol int buff).

As I was pointed privately that there's currently (until the "spec to be announced") a war-only debuff, so you need a war. Coupled with an Unholy knight for haste, you get again 10 people, with warlock optional though (replaceable by a rogue with poisons, but that's less reliable than a curse).

Affliction warlocks will not be using the imp - well, they could, but the way the Felhunter is being retooled, we'd probably end up losing a nice chunk of DPS - and maledicted CoE is equal to Ebony Plague from Unholy DK, and since we're bringing one of those anyway... Ebony Plague also affects all kinds of magic (Not sure what the personal DPS loss for using Ebon Plague compared to loss for CoE is though).

A Dest Warlock, who'll be using an imp and can use CoT just as well as the affliction warlock, would be a better as far as utility goes, even if we assume they manage to do something clever with Affliction scaling to make the DPS in itself worthwhile.

This is the third place I've posted this, but my since the discussion seems to progressing furthest here, I'll post it again.
1. Arms Warrior
2. Fury Warrior
3. Moonkin
4. Enh Shaman (using WoA totem)
5. Ret Paladin (with BoK)
6. Frost DK
7. Mage
8. Disc Priest
Depending on mage spec and priest and mage talents, the spellpower buff may be a lame version. You miss out on RAP buff (unnecessary, the only people who need it bring it), casting speed debuff (usually not necessary, mage may bring), and I just realized you're missing the 3% healing recieved buff. So I guess notch it up to 9 with a tree or a prot paladin.
9. Tree Druid
If the frost DK is tanking, that's a full 10-man raid with a 10th slot open, albeit weak on healing. If it's the core of a 25-man raid with 2 MTs and 7 healers, that leaves 10 "free" slots open to invite friends or min-max as you choose.

The problem of using a single paladin is that you're missing on Blessing of Sanctuary. It doesn't stack with the disc priest's Grace, true, but it applies to the whole raid, while Grace applies only to the MT being healed. I've tried to shy away from buffs that don't apply to the whole raid when trying to optimize who brings what.

if you're willing to sacrifice some buffs/debuffs (that benefit the whole raid, not just the class that brings them), then yes, you can probably work a smaller core to build a workable 10-man. I suspect we'll see a whole class of optimisation applications for that case. 25 man, except in massive stacking issues, are good; the worst combo I've made who bring all buffs/debuffs is 14 specs.

You would miss the 10% crit debuff then. Usefulness depends on the other classes in the raid of course, but at least there is a balance druid.

I believe you can improve on this as follows:

1) Prot Paladin
2) Frost/Blood DK specced into both Abom's Strength and Imp. Icy Talons (note: this may be an awful spec)
2) Arms Warrior
3) Fury Warrior
4) Moonkin
5) Ret Paladin (with BoK)
6) Mage
7) Resto Shaman (specced into Enhancing Totems)
8) Disc Priest

with two swing slots open. You may still be missing casting speed debuff.

A Ret Paladin will not have Blessing of Sanctuary. It's unlikely that a Holy Paladin will either, though more possible until Blizzard makes Beacon of Light an attractive talent.

If you're willing to forego Divine Storm and go 50/21, then yes. Or BoK for the ret paladin, BoS for the prot paladin. The point is, you need two paladins for the full raid panoply, because you need two Blessings. You can get away with only one, if you're willing to sacrifice a buff, which is probably worth it for a 10-man raid (in that case, I'd drop the warlock and the prot paladin, freeing 2 slots at the price of a buff and a debuff that are not always useful - if your boss doesn't cast and has little to no adds). But, as I said, I was looking at the core, the minimum number of people to make a raid with all buffs/debuffs - then you complete as needed.