“The GOP establishment did everything it could to block Trump’s ascension in 2015-16, but they simply couldn’t overcome his overwhelming support among grassroots voters in the primaries.”
You contradict your own argument — that the GOP leadership will force Trump to choose a vp of their liking.
They're not going to force Trump to do anything. They're going to do it themselves.
Do you seriously think John McCain (for example) decided on his own to pick a running mate in 2008 who he despised?