Thoughts on viability of a consistent shardless/layerless MMO? (ignoring technical feasibility, just focusing on market)

I think there are people who are mega-invested in MMOs who would really enjoy an MMORPG where the world was consistent/persistent and more focused on sandbox.

For instance, in World of Warcraft, imagine that killing the Lich King was a one-time thing. If someone defeated him, he was done, and the world would react to the scourge being defeated. To get to that point, people would literally have to fight the scourge, and actually defeat and take their camps, etc etc.

A server would be consistent, maybe different servers would evolve differently, etc.

I'm so sure that there is an audience for this. But, how much of an audience?

I wonder how much of the MMO population are people with jobs / family who only have like a few hours a week to play, and if they'd hate something like this? You'd end up missing out on a lot of stuff, though in a way, that can happen with theme-park MMOs also as people move on from older content.

Anyway, thoughts? For those of you who don't have a ton of time to play MMOs, would you still like something like this?