Charlie Baker will be the lead establishment candidate, Ted Cruz will lead the Tea Partiers. Rand Paul will also do well in the polls.
Lol Baker is way too liberal for the modern GOP and will have no major conservative accomplishments to run on even if he manages re-election.
I think Greg Abbott would make for a strong establishment candidate. Tom Cotton looks good on paper but I don't think he'd cut it under the national spotlight.
I could see Tim Scott running as the token black guy. Cruz will definitely run again if he doesn't win the nomination this time around. If Paul doesn't run again some other sad lolbertarian will try and take up the Paultard mantle, only to perform even worse.