Well to be fair weren't Black and White said to be reboots for the series? So I guess they could break the three versions tradition, just like they broke each main game having a special area in gamecwith a limited number of balls to catch Pokemon in B/W.
woot21 out dawgs
They could, but a third version is not only an opportunity to make more money, but also to improve. Reboot or not I definitely don't think they'd be rid of the third version.