Lunardi updated his bracketology today. UNC is still a 4 seed. Their out-of-conference schedule is going to allow them a high margin for error, unfortunately. Arkansas, Tennessee, Michigan, and Ohio State are 4 wins over top 50 teams.
As far as mid-majors, yes, it royally sucks for them. Gonzaga is significantly more fortunate than a typical mid-major. P5 schools sometimes shy away from mid-majors (especially a home-and-home series) because they see more risk in losing to an average/mediocre team. If you lose to the Zags, though, no big deal. They're consistently a top 25 team. So scheduling them is actually ideal for power conferences. Also, Gonzaga can typically count on 4-5 resume-building opportunities between Saint Mary's (top 30 team) and BYU (top 70)...
Con-USA, A-10, and MWC are good mid-major conferences that usually have a few good teams (Middle Tennessee, W.Kentucky, Rhode Island, St.Bonaventure, Nevada, Boise State). It's teams like New Mexico State, Buffalo, Louisiana Lafayette, Vermont, and South Dakota State that really have to capitalize on those top 50/100 games. They are very few and far between. And on top of that, the committee usually doesn't believe these types of school have enough quality wins to merit anything higher than the best seed for mid-major automatic qualifier (which is typically a 12-seed). Not surprisingly, though, these 12 seeds always seem to win a game or two.... And now Power Conferences are wanting to go to 20 conference games, which will allow them to get a bigger piece of the pie, as mid-majors struggle to find quality OOC games.