This is a great decision for the US game industry. Sony has a ton of exclusives, many from acquisitions, and strengthening XBOX will help maintain a competitive gaming market which should lead to even better exclusives in the long run. Some of the best rivalries in the history of gaming came from different sides with hard hitting exclusives (SNES vs Genesis for instance).
While Microsoft has promised to keep Call of Duty on the Playstation, I think it would be totally ok if they stopped doing that in the future, as any other Activision-Blizzard game; after all, Uncharted and Last of Us aren't available on the XBOX either.