If he's the same player he was as a sophomore, then yeah, he will see his minutes reduced. But I don't see any reason to believe that will be the case given the upgrade in coaching and the fact that he's a rising junior. That's when a lot of players make a jump.
You have 120 minutes to spend 1-3. Provided Gilbert is healthy, that's probably about 30 for him and 35 for Adams. That leaves 55 minutes for Vital, Smith, and Wilson - assuming Wilson spends some of his time at the four, you could still be in the neighborhood of 25 minutes for Vital.
A lot of the improvement Vital makes won't show up in the box score. That's one of the luxuries of depth - you don't do the dirty work coach wants you to do defensively and you find yourself on the bench. Once you account for the massive difference in circumstance, Vital's trajectory starts to look a lot like Albert Mouring's. If he can average double figures, shoot around 40% from three, defend, and mix in just enough complementary play-making, professional scouts will take him more seriously at this time next year or the year after.