Not exactly an NDSU fan, but I can speak to them. Craig Bohl, the current coach of Wyoming, built a great program. He recruited well enough for an FCS school, but he was really, really good at getting the most out of his staff and his team. After beating a couple of FBS teams, recruiting was heating up more and more. That included sniping some players with FBS offers (and I think some FBS tranfers, but don't quote me. That just added to it.
Bohl had Brock Jensen as his quarterback, and while he wasn't some sort of generational talent (he washed out of the CFL in 2017), but he was smart, efficient, and could make the big play when they needed him to. The team played old-school smashmouth football. They had an incredible defense and a great running game. Many of the players played together for the first three title runs.
Then Bohl got the job at Wyoming and Jensen graduated. It didn't look great for NDSU. People figured they still had the talent to do well, but they had a ton of turnover. RB Sam Ojuri, QB Jensen, WR Ryan Smith, OT Billy Turner, OG Tyler Gimmestad, CB Marcus Williams, DT Leevon Perry, DT Ryan Drevlow, DE Cole Jirik, and others for a total of 30 graduation seniors (and of course their new head coach, Chris Klieman). I remember people down in Fargo having crazy expectations, but the rest didn't think they'd repeat again. I personally thought they'd stink.
It turned out that Wentz was a stud (and a straigt upgrade), RB John Crockett could easily cover for Ojuri leaving (with almost 2k yards on the ground in 2014), and the defensive core was still just as strong, and the snowballing effect it's had on recruiting has led to the continuing dominance.
They haven't missed the playoffs since 2010 and probably won't this year. Next year, the 2019 season, will be a test for them as the heir apparent for senior QB Easton Stick hasn't made himself known. There are two other QBs on the roster (both redshirt freshmen), but they're a little ways away from being ready. They also signed Trey Lance, a dual-threat QB from Minnesota who will likely redshirt this year and could compete (and possibly win) the job in 2019. Other than QB, they've got a ton of talent lined up for both 2018 and beyond. In fact, their 2019 recruiting class was pretty nuts. They beat Iowa and some other big Misouri Valley schools for Saybein Clark, a 3-star RB. They also signed a WR who had offers from multiple Ivy League schools, which isn't exactly an indicator of football ability, but he's definitely smart. They've also got a LB commit for the class of 2019, Luke Weerts, who has offers from Kansas State and Cincinnati. He has said he won't be doing any more visits or talking to anyone else. Of course, it's recruiting, so we'll see.
But yeah, on the NDSU note, they're very, very good and have created a machine that draws in players very well. I think that what will eventually shut them down is Klieman getting his shot at an FBS HC gig. NDSU is his first non-D3 HC job, so it might take a little bit of time to dispell the belief that he's riding Bohl's coattails, but it's almost silly to say that he isn't a great coach. He did just sign an extension that puts his contract expiration at 2023, but it was essentially a pot sweetener that gives him $50k if he's still the Bison's head coach next Jan. His buyout's only $150k (and he has a total compensation package that tops out at $475k), though so if an FBS team wants him, they'll likely get him. It's hard to turn down someone tripling your salary and $150k is barely a deterrence.