He will disappoint me if he does. That is surrendering to Bush. As a Republican with no 3rd party out the gopes only have to keep him from getting outright majorities in at least 8 state primaries to preclude him from consideration at the Convention
And,if they pull shenanigans, he can take his case to the American people and tell them why he has changes his mind to run 3rd party. I believe he will keep up his end of the bargain - if they uphold theirs.
The window to run as an independent is over in November because of Texas so it doesn’t matter much.