Cruz is so arrogant that he probably thinks he has set himself up nicely with the GOP for 2020. But the only reason he got any attention and tepid endorsements is that he was the last one standing against Trump. They won’t support him in 2020 any more than they did it early 2016. He’s now less popular than Lindsay Graham.
Yep. The way I see it, Trump kept his word by giving Cruz his slot. Cruz didn't keep his word by refusing to endorse.
The damage is more than that. This sort of speaking slot can be a launching pad to a presidential campaign. The one in the Dem convention in '04 gave us 0bama. Cruz took his launching pad and turned it into a self-absorbed playpen. He'll regret it if ever he figures it out.
Ted Cruz is the Frank Langella character in this clip from “Dave”:
https://www.youtube.com/watch?v=pOgf3IaWlgU