Michigan has no reason to be concerned about Rutgers any time soon. Even the 2014 game only happened with their one good team they had in the BigTen and Hoke's worst/last year and an unexpectedly good game from their QB that night. As it is, Michigan already gets some of NJ's top recruits, most notably Peppers and Gary.
Rutgers can be good enough to beat Indiana and Maryland and occasionally scare the top half teams in the BigTen, just as those two teams have done. However, from my experiences from having gone to a few Michigan @ Rutgers games and my first Michigan sporting event I attended in person was when they beat them in the NIT Championship, I just think there is so much apathy and frustration that will prevent them from becoming relevant. Furthermore, people in NJ are predominantly pro sports fans, and even among college sports fans, they're collectively outnumbered by other BigTen / Big East / ACC fan bases. I can't think of another state with at least one power conference program where that is the case (maybe MA with Boston College?.... Even MD supports the Terps reasonably well).
Even with their basketball program's recent modest rise to competitiveness, I think the occasional NIT appearance is their ceiling (they have the longest NCAA tournament drought of any power-conference (or other regular multi-bid conference) program last making it in 1991). For comparison, I think Northwestern's 1 trip came under very fortunate circumstances considering they had a number of close wins that year include the winning over Michigan that clinched that I was there for, and I don't think Northwestern has much hope of getting back, either, even with their renovated arena, unless they somehow replace Collins with a proven winner.
I realize they don't get a full payout from the BigTen yet and won't until 2027. Maybe if they realize they have no chance at becoming competitive by then, they'll give in and go to the American Conference (or BigEast like Connecticut is doing....). It wouldn't be unprecedented, of course (Tulane & Sewanee left the SEC, Idaho & Montana left the Pac-10, Chicago left the BigTen, of course). They're not very competitive in many non-revenue sports, either (I think they've finished last amongst BigTen teams in the NACDA standings every year), with women's basketball being the main exception.
