I'm assuming he and his agent's strategy would be to approach his free agency as if he's a full-time back that was in a part-time back role because that's what the coaches wanted.
I think it's highly unlikely a player with his talent is going to say "yeah, I'm basically Darren Sproles". They'll likely be looking for a team that is going to treat him (and pay him) like a feature back.
The question is - will there be a team that sees him that way? I'd imagine so. He's really, really good.
Well, yeah. That's what he'd do - he'd just wait for his free agency.