So, this deal is only applicable to the new IP. Theoretically, they can do other projects for other publishers, though not any time soon.

I really don't see what can go wrong. The only thing Activision can do is sue Bungie. They can't directly intervene. No internal investigations or security thugs camped outside the studio. No whoring out the IP to Treyarch. Seems like everything is kosher. If IW had it this good, they'd still be happily under Activision's umbrella.