I'd be interested in a Bethesda-esque game that took place in a cyberpunk setting akin to Deus Ex or Syndicate, where you can upgrade yourself with a variety of cybernetic powers.
An urban fantasy setting would be cool too, like what's being done in The Secret World. Have it place in a modern day city besieged by otherwise not-so-modern demons, cultists, and magic.
I'd also add space opera with the ability to travel to multiple worlds via spaceship, engage in dogfights, and fight on the ground using guns and such...but that might be a
little too ambitious.
An MMORPG. That would really lampshade just how bad they are at game balance and rulesets, and hopefully make them take some actual measures to improve on that point.
Except all they would do is improve the stupid MMO.