In a recent interview, when asked about the future of the Gears of War
franchise once the main trilogy is done and dusted, game director Cliff
Bleszinski stated that the emergence of some form of spin-off or sequel
would be “business 101.”
Gears 1 and 2 sold about 6 million copies, so if [Gears of War 3] comes
out and, God willing, sells 8 or 10 million it would be completely dumb
to not do another one, right?
Despite the series’ initial narrow approach towards narrative, over the
past few years the Gears of War universe has continued to expand via
print media, including a line of comic books and graphic novels which
have played a part in influencing the series’ third installment. We
wouldn’t be at all surprised to see Epic lead gamers into a fresh GoW
story arc as soon as Delta’s draws to its much anticipated conclusion.
http://www.thesixthaxis.com/2011/07/19/gears-of-war-4-its-business-101/