I don't think Cuomo will run. I think he's finished in 18. I wouldn't rule out Sanders giving it another shot either, or Tom Wolfe of PA. On the GOP side it's a big if if Rubio holds onto his senate seat, I think that Sandoval is a possibility also, also Rob Portman.
Cuomo is finished if he runs unsucessfully for a third term as NY-Governor. If he steps down or gets reelected in 2018, he’ll have a shot. That Gov. Tom Wolf (D-PA) throws his hat into the ring is unrealistic in my opinion. He’ll be 72 in 2020 and I doubt that he has any desire for higher office. He’ll be happy to serve two terms as governor. However, he might end up as running mate for a younger candidate (like Booker, Castro or Heinrich).