18 months aren't going to tell you anything other than whether or not they can rebound from next year. As for national prominence, they could be 26-4 and ranked 8 next year, then fall off the next year when Jalen Adams leaves.
Regardless, Ollie is going to cycle through his classes and have breakout years when they stick together. So far, Caliparis one-and-dones haven't done anything for the fanbase than that 1 national championship with the superstar stud of a player. UConn is going to make a run every 3 or 4 years as always.
18 months will tell us whether KO and the staff can coach players "up" - I have seen little evidence of this in his tenure (yes, there have been a few examples, but this is not a strength of this staff). Personally I think a few staff changes need to be made and at least bring in someone with success improving big men.
18 months will give us one more crank of the wheel to see if we can overcome brutal AAC SOS/RPI issues.
18 months will tell us whether we can get back to winning percentages in the range of the low-700's versus where we have been in the 680's under KO.
18 months will inform us of another recruiting class and whether we can get another top-25 recruiting class. I think we can and we need it, but let's see. Top players want to play in top leagues and the AAC is not that.
18 months will tell us about home game AAC attendance. Can supposed winning overcome lame opponents?
They could, as you noted above, be 26-4 next year, but they also could be 21-9 (which is a .700 clip and not bad). I love Jalen and I think he can be a decent NBA'er but I don't think his departure will create a deep drop off (given what else they will have on the roster).
The next 18 months may cement whether we are operating as a top-40 program in a very pedestrian BB conference or operating as a top-20 program in a very pedestrian BB conference. Big difference in my book. And as fickle as the many within the CT sports crowd can be with many "local"pro sports options, we can't slip into top-40 level.