Will be interesting to see if he can make a team. I do know the Seahawks have met with him before and are at least somewhat interested.
I think if he's got a shot it's each what you said - special teams and maybe become a RB.
It's a gutsy move on his part because it's nearly impossible to cross over sports like that unless you're a kicker, so failure is much more likely than any kind of success.
Everything he knows as far as running and tackling he has to adjust, basically relearn everything. All of the fundamentals are totally different. Like watching his video's when he runs he runs straight up, thats not how you want to run as a RB in football, have to stay low, the footwork is different, etc. I would be amazed if he can make a team and contribute.