When Roy faints a few more times and finally retires, don't see UNC is f-ing around with mid-major coaches. Kentucky and Kansas don't waste their time with potential; they hire coaches who they know will get the job done. UNC is arguably an even more attractive job than those schools.
The first call from the UNC decision-makers is going to Brad Stevens agent. I can see Stevens going back to college basketball at some point, and he knows that he could win multiple Nattys at UNC. If Stevens doesn't want to return to college at that time (or has already taken a job like Kansas), literally every great coach is on the table for them (Chris Holtmann, Chris Mack, Mark Few, Dana Altman, NBA guys with college experience). UNC should have learned from the Matt Doherty debacle that it makes no sense to limit yourself to coaches with an UNC connection as that is about the only way the UNC program can crater.
Miller's only shot at UNC would be to get at least on the level of a VCU, Seton Hall or Butler, and stringing a few successful seasons together there. I don't see the timeline working out for Miller on that plan where Miller would be UNC's next coach as I would put the over under on Roy leaving UNC at 3.5, and don't see Miller getting that next job and adding to his resume at his next coaching stop by the time UNC is looking. Miller's only 37. So, maybe he will be a legit candidate for UNC by the time the coach that succeeds Roy is ready to leave, but Miller won't have the credentials for the UNC job soon enough to succeed old Roy.
As for Duke, K is picking his successor, and like almost every job where a legend leaves, his successor is doomed to fail. Of all of K's "guys", always had the feeling that Amaker was the one he was closest too. So, my guess is that Tommy will get the job, and Duke will decline. Maybe, at that point, Duke's decision-makers will realize that its stupid to limit the pool of coaching candidates to just K's brood, but as long as they limit the pool, that's good for everyone else.
Fastest way to tank an elite program is to exclude the very best options to lead that program. Bama learned this in football. Initially after Bear left, Bama tried to hire "Bama" guys with poor results (for them); then, they just said "f-it", lets just get the best coach, even if he has no Bama connections, even if he used to coach LSU, and Bama has never looked back.