From everything I have heard, it appears that Congressional has made it abundantly clear that they are willing to host the tournament on a one-time basis. The folks at Congressional are passionate about DC area golf and realize the importance of bringing a PGA Tour event back to the DC area. The tour would have to take the tournament elsewhere in 2008 though, because Congressional has one or more course renovations on tap to prepare for the US Amateur.
If given the opportunity, I would be suprised if RTJ would turn down the chance to host the tournament this year. However, I have no idea if they would be willing to host the event on an annual basis.