Ted Cruz is owned by the GOPe. Mitt Romney heads the new Cruz handlers of Jeb Bush, Neil Bush and the whole Bush election team. Cruz will leave the stage when he is permitted or allowed to depart. Ted Cruz owes the party elites for their help with poaching delegates and contacts wherever needed in addition to their financial aid.
Kascich also has reasons to stay in, which seem to be in his personal interest and not for the purpose of advancing a fair convention in Ohio. He is not concerned about Hillary winning any more than the elites are.