There will be features and content you haven't even considered.
I see alot of posts since the announcement saying I hope they bring X back or I hope they don't have X in the game. Even quite a few saying I hope they have X from another game.
I think the likely hood is that this game is going to attempt it's best to reinvent the MMO. To do this, most of the gameplay and content and systems are likely to be completely new.
It's likely not to tread on the toes of guild wars 2 at all and to do that, it's not going to be a traditional mmo in many ways at all.
I'm hoping we will all be surprised and say the following
"Wow, why hasn't another game thought of this already that's genius"