The deal is ... that doesn't matter. If we all leave the republican party. They'll nominate whomever they chose and then in November we'll vote for who they nominate, or we'll vote for Hillary..... or we'll vote for a libertarian. Or we'll write someone in. That hasn't changed.
Look at it this way... there is no advantage to the republican party if you stay a registered republican. Heck, most states even have open primaries.
I've always voted for whomever I thought was the best candidate in the various elections. Haven't you? Nothing changes if you and I leave the party.
The Gop has been so unfair to Trump, if they steal this thing, I hope he runs 3rd. party. He will win!