Republican Party will go the way of the Whig Party. People like McConnell, Cornyn, McCarthy, etc will never willingly give up control and the base will not accept them as representing their party. If Trump is nominated I expect a so-called moderate Republican will run against him as an independent in the General election ensuring Democrat win.
If Trump is ousted or does not win the primaries then his loyal followers will stay home and the Democrat party will win the election and at the state level.
We are in a mess as true conservatives. Fighting among ourselves is exactly what the left wants.
This is why trump should have formed a whole new party. Most if not all of his supporters would have immediately joined it. The GOP would have instantly become 3rd.