Their is no good reason to stay in the race. Cruz is hoping for enough delegates to possibly make a deal with Kasich and Rubio. Kasich is only holding on for the Ohio delegates. Kasich dropping out would end the delegate game the same day, as the Ohio delegates would become unbound from Kasich and be bound to the runner up (Trump). Kasich’s play is more for himself than the GOP. He is trying to get something out of it.
I think Kasich wants the VP slot on the ticket.
Worrying about Cruz staying in the race is sign of insecurity. Is Trump so weak that continuing to contend is problematic? It’s not as if he is going to run out of money. IMHO, it will h lip him to further refine his message.