I think Rubio and Bush will be dead soon, at this point it is just Trump and Cruz the rest do not matter.
Not sure. If Cruz stays in and Bush and or Kasich leave Rubio will be tough to beat. Trump may consider being conciliatory to Cruz and remind him that they may have more in common than not
If it were Trump vs. Cruz or Trump vs. Rubio and the rest of the field were out - Trump would be out. Unfortunately, the supporters of the non-Trumps are splitting the rational vote and leaving Trump as the “winner”