WWE's official press release that Smackdown is moving to Syfy reveals the bad news that NXT will leave the network in October 2010 when Smackdown joins it. In the press release Dave Howe, the President of Syfy, gave insight into this decision:
WWE is the ultimate in imagination-based sports entertainment. The fantastical thrills of Friday Night SmackDown provide an ideal addition to the Syfy slate, as it targets the younger male and female demographics, which are the fastest growing categories for WWE. With Tuesday night, a proven winner for our original drama series including Warehouse 13, there is bigger opportunity for series such as Stargate Universe, Sanctuary and Caprica to thrive on a night with a significantly larger number of viewers available to watch live.
I would interpret that to mean with NXT's current so so ratings for the network, that there was no room left for it on their schedule, and that they're keeping Smackdown on Fridays because it is a proven ratings success on that night, while believing that there is more potential ratings growth for their flagship shows on Tuesday nights. It can be speculated that perhaps two prime time wrestling shows was too much for the Syfy executives to stomach, given that their network still specializes in science fiction, fantasy, horror and paranormal programming.
James Caldwell of the Pro Wrestling Torch is reporting that WWE has found another network for NXT. The favourite would be WGN, which already airs WWE Superstars and has made a bid for Smackdown in the past. So it looks like everything will pan out OK for WWE.