I think it will still retain the Gears of War title - but probably a whole new war, whole new story... in the world of make-believe anything is possible :) - also don't we have that mysterious Gears of War EXILE thing for the Xbox LIVE Arcade at some point??
Well, Epic have repeatedly said that they'd love to continue the Gears universe, and considering how much more there is to it they've got plenty to play with. A prequel set either during the Pendulum Wars or E-Day would seem to make sense.
Whether it would be a launch title for the X720 is another question. I posed up some news a while ago about an Xbox magazines "the Insider" column which said they'd heard reports that Microsoft were lining up launch titles and that Gears 4 and Forza 5 were