Cruz needs to drop out now.
So that Trump can put forth even less effort than he is already putting in? Does it not bother you that Trump is perfectly content to abstain from the delegate selection process, letting the GOPe seat his delegates for him? So when it comes time at the Convention to change the rules and bring down the GOPe, all of Trump's delegates will be voting to protect the status quo. And to hear Trump supporters exclaim how Trump will bring down the GOPe. They are totally clueless.
There is more at stake here than winning the GOP nomination. Ted Cruz recognizes this. Trump could care less.