It is likely to say that they are moving away from bring a certain class for a raid buff. In the game now, if your raid only has 1 Shaman or no Shaman, you can grab a 70 Shaman in blues and they'll make a contribution to the raid just by buffing the damage of 4 T6 DPS. This is bad because you're probably sitting out a good healer, tank or DPS class for that crappy shaman.
They're giving everyone raid buffs now. This means they don't have to balance a hybrids DPS against their buffs near so much. If they do it right, like a couple others have said, every DPS spec will be comparable in damage. You've got all the raid buffs you need with a few players, and everyone else does comparable DPS. It's a game bigger than anything anyone makes, they might get it wrong. If they get it right, though, raid leaders will have a lot more flexibility than ever.
Excessive raid buff stacking amplified the DPS difference between classes, which means that this won't be the case allowing individual skill to shine. There is nothing overtly intelligent and challenging about deciding raid setups; it all comes down to what you have available. Forcing people to recruit specific built and classes to progress effectively and binding the fate of a raid night to who logs in was moronic.
The fact that the game becomes more casual friendly does not mean that the hardcore aspects are diminished. Mostly on raid encounter, what define a hardcore effort are not the farming or the excessive min/maxing but rather the quality and quantity of effort. Great guilds have great players who can work hard on an encounter for as much time as needed. In TBC you pretty much had to bench all your melee if an enhancement shaman was not around and anyone not in his group would suck. Entire raids would get cancelled if key members did not show up not because they were good players but because they had the specific buffs needed. Spreading those buffs around which means that people have to pick a class because they enjoy the playstyle and are good at it; not because the class is rare/extremely useful/offers a unique buff.
Blizzard has said that they will increase DPS on some of the lower classes. From that post, it basically said some will need an increase in power and some a decrease. That's a pretty open ended statement that really means absolutely nothing.
But while we see some benefits of raid wide buffs and debuffs and so on. It's going to create more confusion and regardless there will still be a ton of theorycrafting on optimal raid set-up, in other words, who gets invites and who does not.
For example, why bring a protection Warrior or a feral, a Death Knight will fill in their slot better- not only will they provide better buffing, better Area of Effect tank capabilities but they will provide essentially the same buffs an enhance shaman will, thus being able to fill 2 slots. Thus a higher DPS class will likely fill the hole.
In a nutshell, Blizzard has repeatedly said that they will balance class DPS far closer together for all built. Sure some built will be stronger in theorycraft but hopefully not greatly stronger, and that strength will no longer be amplified. This is a change that promotes skill. If you felt that what made your raiding great was forcing raid leaders to pick you for your unique buff and stack 5 shamans then we have different tastes and they are satisfying. We do not need to bring moron Warlocks just because their class is so much stronger than others that they do better with half the effort others make.