Personally, I think that this is much ado about nothing. I fully expect Cruz to lay out a nice conservative vision, focusing on areas that don't conflict too much with Trump's agenda, and then will endorse Trump (but it might be less than enthusiastic).
In political terms, Ted Cruz is a young man and can be patient. If Trump won two terms and Cruz followed him with two terms, Cruz would be younger leaving office than Trump was when he entered the office. Considering only the political angle, Cruz would be probably be best served by being seen as a loyal although dissenting soldier. If the Republican Party splits in this election, I don't think Cruz would want to be seen as the cause.