Earlier, I posted something indicating that Trump's violent rallies served to warn party officials that if they tried to rules-monger the convention in order to take the nomination away from him, violence would ensue.
Trump is pretty much saying it directly.
Trump is the nominee.
The conservative movement has incentives to destroy the Republican Party so that they can rebuild from scratch, but the party officials don't. The ones who have positions of power now have no reason to tear down existing power structures in the hope that they would achieve similar positions in whatever rises from the ashes.