According to The Wrestling Observer Newsletter, WWE's current deal with NBC Universal is set to expire in September of 2019. It's being reported that WWE officials, including WWE Chief Operating Officer and Executive Vice President of Talent, Live Events and Creative Paul "Triple H" Levesque, recently met with FOX officials to discuss the possibility of a partnership.
Dave Meltzer noted that there might even be some interest from FOX in actually buying WWE, although it doesn't seem too likely that Vince McMahon would want to sell his majority ownership of it.
A big factor in the situation is whether or not the Ultimate Fighting Championship stays with FOX or not. If UFC leaves FOX, then there is a good chance that FOX would want to fill that gap with WWE.
As for Monday Night Raw and SmackDown Live, the word is that Raw would end up going back to two hours on FOX Sports Network (FSN), while SmackDown would likely land on the FOX Sports 1 (FS1) channel.