Well either McSally (likeliest) or Sinema are going to run in 2020 for senator again. That's clear. If you're so close, you'll definitely try again.
If McSally loses, I have a feeling you're going to be seeing a lot of Trumpists and right wing pundits (when they're not making false claims of voter fraud) claiming that they lost the election because they ran an "establishment" Republican instead of someone like Kelli Ward or Joe Arpaio and they'll nominate someone like that next time around... We saw that last year in Virginia when they were saying that they should have nominated Corey Stewart instead of Ed Gillespie which lead to Stewart being their senate nom this year