I don’t believe Cruz can win at this point.
I DO believe the Establishment will try to use him to prevent Trump from getting the necessary number of delegates to win on the 1st ballot. If they’re sucessful, they’ll toss Cruz under the bus and attempt to install one of their favorites (Romney, JEB, Kasich, etc).
We’ll see.
More likely, they will make a deal with the devil. They will let Kasich and Rubio give their delegates to Cruz. (Kasich and Rubio have to stay in until the convention for this to work, otherwise their delegates are released). Cruz will have to agree to an establishment supervisor as his VP, and he will have to agree to certain conditions about what he will do as President (amnesty for starters).
I think that the addition of Neil Bush indicates that such a plan is in the works, and that Cruz is willing to go along with it. Cruz could be allying with Trump instead, and be guaranteed of VP. Instead, he is throwing in with the establishment. It is now Trump, and only Trump, against the GOPe and for the American people.