I'm going to against the general trend here, and suggest something original, rather than just list some silly wish-fulfillment fantasy spruiked by the fan fiction writers with no concept of licencing or copyright themes.
One of the greatest injustices in gaming is that Obsidian has barely been able to make their own IP.
I'm not really a fan of old-school RPG turn-based combat systems (it's kinda insulting to turn hundreds of dollars worth of silicon into a pencil, paper and a 20-sided dice), but I'll live with it as long as we get the sweet non-linear, multithreaded narratives and unique characters Obsidian's famous for.
Also, the entire Holy Trinity (Avellone, Sawyer, and Urquhart) must be fully involved!
Personally, I wouldn't mind a cyberpunk game, but that's my personal preference and I really don't like giving orders on creativity.
At any rate, I'm sure you'll do well, and no matter what you decide, you'll have my money - if only to support artists who are breaking away from the publishers and doing what they love.