No such thing as a free epic
Totalbiscuit recently pondered the effects of the attunement chain in the Burning Crusade. One side-effect of such an extensive attunement chain is that raiding is limited to your main character only.
Let's assume that you belong to a raid guild that's halfway through Tempest Keep and you get tired of the fireball spam / healthbar whack-a-mole / buffbotting and want to try out other roles as well. In classic WoW, you could always roll an alt, powerlevel to 60 and jump back into raiding. Thanks to the attunements, jumping back to the raiding is easier said than done. You just can't jump into MC or BWL in greens, stay out of the way and pick up some epics. To even zone in to Tempest Keep you need to do Heroic Steamvaults, Heroic Shadow Labyrinth, Heroic Shattered Halls, Heroic Arcatraz and Magtheridon. To get to the Heroics, you need Revered reputation with four factions, which you get from running the level 70 nonheroic instances. To get to three of those, you need keys from the previous instances. Suffice to say, that is a lot of work. Too much work for just an alt. By the time you have completed the attunements, you should already be in full blue gear and spent dozens of hours of game time.
So what does this mean for raiding guilds? Replacing burned-out raiders is going to be expensive. You just cannot "retrain" one of your existing raiders when a critical member quits, takes a vacation or generates enough guild drama to get kicked. It's more worthwhile to recruit (even cross-realm, like TotalBiscuit did by offering to pay for a transfer) a character that already has the attunements and gear.
What does this mean for the so-called casuals (read: anyone who doesn't raid)? One effect that I'm hoping to see is that the envious and confrontrational attitude against raiders will gradually dissolve. Belonging to a raiding guild is no longer a fast-track to epics. If you see someone in T4/T5/T6, they have worked for their gear. Getting epics via raiding is not easier than crafting or PvP, it's just different. And until Hyjal is on farm, the gear you get from raiding is probably more or less equivalent as well.