There's really no way to tell how adding a third team will affect the franchise. You're just assuming it means more COD. It could actually mean that Treyarch or Infinity Ward are getting off to make other games. It could be a team dedicated to a specific platform, like maybe a Wii team, so the Wii releases can be day and date with the HD versions.

I have no idea. That's why I'm not making assumptions. Too often we see something that can be interpreted in many ways and always assume the most grandiose interpretation is the right one. Whether it's an RPG announcement everyone assumes will be for an HD console and it ends up being a DS game, to an announcement from a publisher everyone assumes will be the biggest announcement and time and time again it's just a game no one here cares about. 

There are so many different ways to interpret this that there's no point jumping the gun and making statements that may or may not happen and passing them off as fact. Considering the amount of teams it takes just to make every yearly Call of Duty, it's not out of the question that Activision might be hiring a platform specific team. Maybe they don't want to outsource the DS versions to n-Space, or they're seeing a need to have a Wii specific team to get the games on schedule, or they want to re-explore PSP titles.

Also you have to understand that if they hire a new team, that doesn't mean they can make COD every 6 months. A new team would need the same 24 months the other two teams need, which would mean every 9 months they could release a game, or more realistically, each team might share a three year schedule.