You're wrong for one major reason -- Texas allows early voting (ended Friday). There have been many votes already cast before Donald's recent endorsements, etc.
If there was not early voting, you probably would be right. My hunch is Trump takes a plurality of those who vote Tuesday but it won't be enough to overcome Cruz's lead amassed in early voting.
Those Trump lines are going to be a mile long. The early voting WAS likely mostly Cruz. We’ll see how many really vote for the no-show Senator.