Probably just BS designed to wreak more havoc with GOP. There is no process whereby the GOP could remove Trump as the nominee. So there is no path for them to implement a coup.
The "Coup" is deliberately throwing the race to Hillary. I have come around to believing the claim that the elite Republican Leadership is in bed with the Democrats to keep the Washington D.C. money fountain going.
Trump is a threat to their influence peddling and crony capitalism, and so they would rather have Hillary.
I would rather have an Iranian Nuclear strike on Washington.