Well if the team falters than yeah, the deadline becomes like it did for Hamels, you either extend or trade. But otherwise they're just gonna have to let it play out and they could still sign him prior to other teams getting their shot. Phillies would obviously not have to worry about losing picks if they keep him. Comp pick won't be worth much (assuming they remain a good team and over the CBT).
I'm in favor of keeping of him but of course leery of going too many years. It's possible they could also decided Wheeler's a better long-term bet and try to lock up him early. The big question is really still how much Nola actually wants to stay. It could easily turn into a DeGrom or Freddie Freeman situation.