That's about 70% reasonable, and about 30% total bullsh-t. The reasonable part? Cruz and Carson being outside shots now, and Trump being the most able to shake things up good. No problem with that.
But to characterize Cruz as "beholden to donors" and "confined by the GOP establishment" is just nonsense that you cannot support. And I know how you're going to try, and I ask you for your own embarrassment not to even go there. It's just a ridiculous assertion, and weakens your entire post, which has some validity.
Moreover, Cruz entirely lacks (so far) any proven record of being able to go around or over the media (as seen in the polls), something Reagan did and something Trump (in much different ways) does.
Maybe 20, even 15 years ago, a President Cruz would have no trouble getting his agenda through. Today, very little chance.