I'm sure they would have stayed with the 999 series if it had been selling.
While the current series is so popular they probably can't justify ending it too soon, just for competition.
They spent a fair bit on the 1098 model change, and dropped the selling price as well, which means it will have taken longer to recover costs, never mind recovering losses on the previous series.
Plus they've had to cough up the odd free radiator, sprocket and regulator..
My bet is 2012.