I don't see Romney switching parties.
I just ask myself which party will get him the most attention. If he becomes a dem, then he is just one more dem. But if he remains a republican- as with McCain, Susan Collins, Murkowsky- you get the president and the republican party AND FIRST AND FOREMOST THE MEDIA, catering to your sorry arse on every critical vote. He is a backbencher now in the republican party and would just move over to being a backbencher in the dem party. Or he can be treated like God and the only one who is important when Supreme Court Justices come up, or obamacare votes etc.
He is already walking around like he is bearing this YUGE cross now for being the only virtuous person in DC and will suffer his crucifixion in DC and at home. Give me break. Put a pie in his face and strip him of any committee assignments he may have or might have. If you need votes on critical issues, put some extra dollars and commitments into Joe Manchin. Viewers will recall that a couple times I have recounted all the extra goodies that Lisa Murkowsky has gotten lately. That would be the same Lisa Murkowsky who just voted to acquit Trump.