I'm sure that the human leadership will have some level of coordination with the Predators, but my guess is that Lebbon will keep it to a minimum so as to avoid it becoming cheesy. As far as what will happen after the Rage War, I imagine things will probably go back to how they were before. The Predators don't seem like ones to change!
Then again, we don't know how far out of control things will get by Book 3, so maybe the status quo will be totally altered. I'm holding out hope the dog-aliens will show up in the third book, which could really shake up the balance of power.
Man, when I think about all the stuff coming out this year, I just get so happy. An ongoing comic set between the first two movies, the rest of the far-future Rage War, another A/P crossover with Prometheus, and all the re-releases of the old novels and comics. Things haven't been active since probably '93-'95.