Of course it will.
There's no such thing as exclusive third party between the HD consoles now*.
I believe this and the agent are going multiplat. And Splinter Cell, and Versus... etc.
Want exclusives? Buy the damn studio and IP. That's how it works now, and that's how it'll work from now on until we have a clear winner between the two - which won't happen anytime soon.
*valve and some very loyal second/third party may be the only exceptions. But then again, i wouldn't be so sure. The tendecy, imo, is to get worse.