I wonder how Blizzard will handle future expansions in regards to alts.
My friend did a successful raid spot switch from one main to the a new one recently. Anyone who has raided on one character for a while knows its not always easy to switch to a new character - especially if the old role was one of those abundant healer or tank roles and the new role is the scarce dps roles. But he did so, and is having fun. However he's finding having to re-grind reputation a bit of a pain.
I had a easy time of it on my first 70 because everyone was running everything. Getting different reps - Aldor, Scryer, Heroic, Sha'tar, etc - came rather easily as a part of leveling and doing quests and helping others.
But on my subsequent alts I can't bring myself to run various instances that I've done so many times already I'm exalted.
One player on the general forum (really wish I still had the quote) said something about how having to stick with one character, build upon it and make permanent choices is really what RPGs are all about. There were comments that the alt-friendliness that is counter to sticking to one character is what made WoW successful and gave it staying power. You can't raid at end-game? Roll an alt!
Leveling gets stale, but is still doable. However the things Burning Crusade introduced have made alt playing at endgame slow down, from my limited view. I know of 3 people who play multiple characters at that level and they don't have jobs.
What does this mean for the future of WoW? If anything? I think they'll need to ease up on the endgame requirements. Or maybe that's just my wishful thinking.