I can wish, but I feel that the GOP has shown that no principle is more important than retaining power for themselves

for those who don't go along. The question isn't whether there are any centrist Repubs, but whether there are any who are brave.

While what you say makes sense these people are, after all is said and done, Republicans first and forever. I do not believe they are capable of straying from their ideology.

President Pence - Yippee!!

as observed, the parameters are different now that there's a batshit insane president who will gladly sign off on their idiotic legislative antics
so now they actually have to be a little bit more careful to avoid eroding their anti-progressive propaganda's effectiveness -- in short, they have to actually govern now

They don't get to play the obstruction game any more. They have to write and pass the laws and THEY will be held accountable. 2018 is just around the corner. There are plenty of them who were late to endorse Trump. In some cases very late.

He was defeated by Tammy Duckworth. Collins is the only one who can even marginally be labeled a "moderate." Who else do you think of as "centrist"? McCain? Flake?

Any representative from a state that has a lot of retirees, like Arizona and Florida, will have hell to pay if they vote for cuts to Social Security and Medicare. With the Baby Boom generation turning 65 at a rate of 10K PER DAY, we still have a mighty voice and will continue to for another 13 years.

Bills still have to pass both houses to get to Trump's (or Pence's) desk. We don't have to flip the whole Senate, just a handful.