I'd love to see Frank West in everything. And I do, genuinely mean that.
But what I mean is that I'd love to see Frank West in everything. And I'd want a well thought-out reason for him to be there that is mentioned in passing.
I'd love for Frank West to become a legend in gaming. A sort of spectre who haunts gamers and appears, at random, in nearly everything they play.
He wouldn't have to be playable; he wouldn't have to be important in the plot; we wouldn't have to have any lines; he wouldn't even have to be more than a shadow, lingering too long not to notice as some easter-egg in an alleyway.
Why? Because Frank West is about the most obscure character to do this with that I can think of. It'd be funny.
Also, he's covered wars, y'know.