Can Trump do that?
If so, a good move indeed. Maybe in his 2nd term.....
“Can Trump do that?”
Yes; the President may appoint a sitting Associate Justice to the position as Chief Justice:
Like the Associate Justices, the Chief Justice is appointed by the President and confirmed by the Senate. There is no requirement that the Chief Justice serve as an Associate Justice, but 5 of the 17 Chief Justices have served on the Court as Associate Justices prior to becoming Chief Justice. Three were members of the Court when they were elevated to Chief Justice:
But since all Justices, including the Chief Justice are lifetime appointments, I surmise that Trump could only elevate Gorsuch if Roberts were to leave the Court or die ( which I guess is also a ‘manner of leaving’).