Cruz could be reelected to the Senate for another 20-30 years if he wanted to. Given his personality and inability to relate to actual people, maybe he'll realize his future is on the Supreme Court.
And who would give him the votes to take that job??? Would these be the same republicans who have called him a 'F&$#& @$$****' or 'the most insufferable SOB i have ever had to work with'?
More likely, any notion of putting Sen Cruz on the supreme court would rapidly be re-directed towards putting Sen Lee on said court. You know. Because Mike Lee is actually a *Nice Person* or thereabouts.
Putting Cruz on the court assures two things: 1) that an uncompromising conservative purist on the bench for multiple decades and 2) that only a handful of people will ever have to work with Ted Cruz again. As a bonus, Cruz would rarely if ever be in the media reflexively bashing his colleagues if he were on the court.