Let's just start this right with the most realistic stuff, and then get to the gauzier, giddier aspects a little later in the item...
Obviously there are some complications with the idea of Marshawn Lynch possibly un-retiring and ending up with the Raiders in either a trade with Seattle or after Seattle releases him.
First: Yes, Seattle still has his rights. That might not be a huge hurdle, but it's the first one.
At some point, Lynch and the Raiders - even if they're ready to join up - have to see what the Seahawks will do if and when Lynch announces he is un-retiring and it's possible Seattle will try to hold onto him and see if the Raiders will trade for him.