Single Player End Game

I've always been intrigued with such an idea and how it'd look...

How would itemization function?
What form would encounters assume?
How would the 10 classes fit into such a vision?
How could race and lore fit into the content?
How would the world be affected?
How would such a vision relate to the greater PVE experience?
Could it assume a place in PVP?
Could it cross over into the current dungeon and raid content?
How would this change the greater World of Warcraft community in relation to the original implementations that blizzard has designed for its customer base?
What would be the programming demands for such a change?
What magnitude of change would this demand?
Would it be fiscally possible?
Would this negatively impact blizzards original designs and its customer base?
What positive effects could this create?

If you think of other questions to add, please do.