No reason to doubt that this is sustainable and/or can have a similar stretch like this again for Nova.
One thing that really hit me this tournament (finally) is that rankings for recruits really don't matter at all. There's a clear very very elite top tier of talent, but after that, the rankings are all arbitrary and based on different things. The programs that win are the programs that recruit players that fit and buy into their system. You can consistently win with 3 star recruits and 2nd round draft picks, as long as they buy in and fit.
That said, I'm not sure we have a system.
IMO, the parity came along when most of the high-major teams started consistently losing players to early entry (mainly, teams losing kids after their freshmen and sophomore years). Then, you have mid-major squads who have a ton of a experience with juniors and seniors (maybe, a player or two who have even transferred from a high-major).
You also have many of these kids who have played with or against one another on the AAU circuit for a couple years or more, so there's familiarity of who they're playing against. So, you have the landscape that you see now.
Typically, at the end of the day, the team's with the most or best talent will rise to the top. Villanova has their share of talent, and they're also experienced. Only one team (2001-2002 Maryland Terrapins) has won a national championship without a McDonald's All-American since the origination of the game. Don't get it twisted, as that Maryland team had a ton of talent and was also experienced.