The establishment can see the writing on the wall. Trump is now facing who guys who have almost no votes and two other guys who are both fatally flawed for the general election. Without something drastic happening Trump will almost surely be the nominee. The real panic will come on Wednesday if Super Tuesday goes the way the polls predict.
Still, I am surprised they would go back to Mitt. I am surprised also that Mitt would want to go along with the plan. But old dreams die hard. And these guys are willing to play hard and dirty.
Romney/Dole 2016
They asked Dole first but he was busy...
If Mitt comes in, the deal is off and Trump can run as an independent.