The question I find interesting, in the wake of Ted Cruz's headline-making refusal to endorse Trump as a major speaker at "Trump's Convention," is just what Cruz's strategy here is. Here are the elements with which I'd begin in the search for an answer:
1) Cruz is a very smart guy, easily the smartest (it would seem) among the Republican face-cards;
2) His ambitions have no limits, he is all about growing his power; his will to become president is powerful;
4) Cruz is one for bold, unlikely strategies-- e.g. the way he stomped all over the Speaker of the House to engineer a government shutdown in 2013 over Obamacare, presumably to blackmail the Democrats into let Obamacare be repealed, though he must have known it was a losing battle (it was obvious, everyone not in the right-wing fantasy world knew, it was a losing battle; but much of the GOP base imagined they could indeed kill the demonized Obamacare, and so Ted Cruz became their hero by not "caving" to reality;
4) Cruz must have known that he would arouse anger from the convention, and that his failure to endorse Trump would become an enduring image in his relationship with the Republican Party;
5) So the question becomes: what is the scenario that this clever man -- and out-and-out sociopath -- envisions the workings of this image -- of the stance he took toward the GOP's official nominee for president -- will help him in 2020 get the Republican nomination and then become president? -