It's quite a bit early to be thinking about crossing over things, when neither game's settings are quite set in stone yet. I would, personally, imagine the first efforts at such a thing would likely happen in the form of more traditional media for the genre: a comic or a mini-web-series. This would bypass the technical difficulties.
Shoot no, I wasn't suggesting it for launch! hehe. And yeah, the comic angle would make more sense all around. I just like to think outside the box when I'm brainstorming, and I tend not to place limits on myself based on minor details like "difficulty" or "reality".