In the Republican debates, Cruz would not sink to insults and name-calling. In the Presidential debates, he will eviscerate Hillary since the level of discourse will be higher and focused on policy differences.
I've heard all about how smart Ted is and how he is a champion debater. Maybe so... in a formal debate with judges scoring points.
That is not what a "presidential debate is".
The presidential debates are not a comparison of policy differences. If you believe that, you will continue to be disappointed. Cruz lost every debate with the public. Cruz would do the same in the general election. He has a hard time communicating with real people and connecting with them. He is at his best when trying to be Reagan, but he comes off as a creepy imitation and not an authentic person.
I doubt he will be in the general debate. Not enough people want him.