I think Lynch will be back. Look at the way he's pushing his marketing and ad's right now and he'd be leaving A TON of money on the table and no one is that dumb. Not to mention, JS has already mentioned he'd offer him a new contract and speculation is that it'd be near 10m this year cash (signing bonus and gteed base) so I don't think anyone would walk away from that.
Not to mention, he's at the top of his game right now.
That said, this is Lynch we're talking about. But I think it's 80% he comes back.
if not, I think we need a bellcow back as one of only two teams that focus on the run game as the first priority. I think we should go for Gurley or Gordon at the end of the first round. Those guys can be decade talents in the right system and we certainly have that run first system they'd covet here. RB's typically acclimate to the NFL pretty quickly too so I think we could expect good production right out of the gate. That also means cheap labor at the RB spot for 4 years which would be very nice for other offensive positions that need upgraded.