A) There's lots of other companies working on Infinite (Certain Affinity seems to be taking on an increased role), and B) there's a lot of game development that can be done that isn't the same stuff as sustaining a currently-shipping product (prepro, design, etc.) Not to mention hiring new people for new roles isn't necessarily replacing someone on the current team. In other words outside of arguments about management focus or the like, I don't really see how one impacts the other.