That was last cycle. Obamacare has been in place for a while and a lot has happened. It's not only the establishment, Republicans that actually ran on full repeal, including Freedom Caucus members, have come to realize that many of their own constituents have benefitted from some of the entitlements. They don't want them to lose their insurance and a full repeal will leave them high and dry.Maybe all the primary challengers can run on repealing Obamacare like every single Republican did last cycle.
The votes for a full repeal just aren't there anymore, especially for a bill that includes no coverage for preexisting conditions like the Freedom Caucus wants. I doubt Trump would even sign that bill if it did make it to his desk because that's something he promised would stay.
If new challengers run on full repeal, if they get elected, when they get to Washington, they, too, will have to come to grips with the votes not being there for a full repeal. It's fantasy at this point. There's going to have to be compromise, and common ground, reaching an agreement in the middle, giving both sides something.