I honestly don't care about a new game. Make whatever you want, I'm sure it'll be good. But please oh please make an engine and multiplayer system capable of traditional custom persistant world game hosting. Something in the scope of NWN1 and 2, with a modern scripting system and an easier to adjust (or completely overhaul) rule system.
From 2001 to about 2007, I played nothing but Neverwinter Nights, simply because instead of being forced to play the game that developers wanted to make, I played a game that developers enabled me to make. Another game is great (specially if you can convice sega to hand over the AP license), but I don't just want to play another game. I want to play a persistant online world, that has only 50-70 players rather than 6 million rambling idiots typical of todays online RPGs, in a story world and ruleset of my choice.
So make a fully customizable persistant world SDK.