McCain has already been censured by the AZ Republican Party, and they should move to full expulsion. He has already announced he intends to run again, and with his wife’s deep pockets they can and do destroy anyone who challenges him.
But if he runs, he can run as an independent. Let him caucus with the Republicans, if they will have him, but he will no longer be a Republican.
I almost hope that his former running mate primaries him.