Cruz has a shot at uniting the party. Trump will NEVER unite the party behind him.
He's burned too many bridges.
Now, what he may be preparing to do is reverse himself on most of his policy positions, knowing that his supporters are cultic worshippers of HIM, not of what he stands for. He may make promises of dropping his silly wall, say "never mind" to tariffs against China and Mexico, and grovel in apologies for all the misogynistic remarks he's made about women.
No surprise if he does this. Trump has no core, no values, and he thinks nothing of lying his ass off. I would fully expect his Trumpkins to just roll on, not caring a whit that he would show his truly liberal inclinations and expect them to go along with it.