The only path Cruz had was the south. Since that didn’t happen, he only remains for one purpose, to keep Trump from getting 1237 delegates. Given that strategy, his only hope is a brokered convention, which would still leave him out.
For now, it does benefit Trump to have multiple candidates.
Tin foil hat time. Cruz and Rubio fight Trump until March 15. If Rubio loses FLorida he will “suspend” campaign for few weeks and give Cruz a shot to take down Trump 1 on 1. If Cruz can’t beat Trump Rubio will jump back in the race and campaign for brokered convention. I wonder if that is possible under RNC rules?