Any meaningful new mmo has to9 figure out a way to foil multiboxing. It drives away audience.
I like the skill paths > class idea ukerris mentioned above and if designed well, sure, it would be a fine way to go.
What still remains the challenge in the pve model, is how to design content.
What kind of irks me, is encounter mechanics can get ridiclously complicated but people just adapt, and that is where the fun curve really goes down because an encounter can turn into a strictly scripted series of raid actions, and for some, like me, that is where I get bored.
So the key, imo, would be to design content that gets more complex as the game evolves, but where the encounter becomes adaptive and starts to fuck with how it is dealing with the raid past certain parameters.
I'm not inventing the wheel. But I am asking, why the fuck can't design AI's that are less predictable after a few runs. You know, like being able to time Rampage? That is just a nerf, there is no reason they could not code more complicated triggers for effects like that.
The ideal would be that no website would be able to give you hard and solid strats, because the encounter reacts and can be tweaked on the fly by the devs. Not to make them more difficult, necessarily, but just different -- that makes people have to play on their toes and not just run through a script.
There should be as little script as possible for encounters the higher up in the game they go.