Trump was convinced that he had to take Pence to get Evangelical support. He has doubtless deeply regretted that decision ever since, and certainly doesn't think he "needs" to win over Evangelicals or establishment Republicans. I'm also skeptical that he will choose anyone he sees as a possible rival (aka. an older white male perceived as successful), and he isn't going to let what's left of the GOP establishment dictate terms to him.
He's going to pick someone he likes, who doesn't seem threatening to his ego, and who he perceives as giving him an edge. He might go for a younger white male who offers sufficient flattery, but a non-white male candidate like Allen West or Kristi Noem, who is sufficiently ingratiating and flattering, seems more likely to me.
I wonder how picking Gingrich or Christie would have went in 2016. Doubling down on your strengths as a loud mouth tough guy could work. It worked for having two moderate Southerners in 1992 for the Clinton/Gore ticket.
