looks like the next "gears" game will be announced monday at E3 during the ms briefing. Hopefully its at LEAST a year or two off though, there is still plenty of life left in gow3.
Possibly prequel material. I wish theyd got a bit further back, id love to play a gears game set in the pendulum wars! http://www.oxmonline.com/new-gears-war-game-debuting-e3