Had Trump not run this election cycle, would the establishment have been able to fend off the Tea Party and other anti-establishment movements?

Essentially, is the chaos in the GOP a result of Trump specifically, or part of a wider anti-establishment sentiment? Had Trump refrained from running, would we be hearing about party elites resigning themselves to a Cruz or Carson nomination?

On one hand, Romney faced a series of attacks from the right in 2012, and one could interpret what is happening now as an extension of that. However, the establishment successfully nominated Romney in 2012, and without much difficulty. Cruz has a lot of support now, but how much is real and how much is tactical voting?