This is a great topic, because it requires that we talk about our view of the future, which means we can disagree endlessly, with no one ever being right...until proven so years later.
I am one of those who has little doubt that membership in the AAC will eventually affect UConn's ability to recruit the best players long -term.
You're right, there's no question UConn has a nice haul of students coming in, and things are already looking pretty good for the following year. I'm really looking forward to seeing how this team comes together. But recruits are coming to UConn because right now, UConn is riding as high as a college basketball program can.
Now it is possible (though I would argue unlikely) that UConn can become a thriving major-league team in a mid-major conference, which is something I don't think we've seen in a long time. If they can, in essence, create their own brand for men's and women's basketball -- become, as Geno says "in a league of our own" -- then it will be unprecedented, and all bets are off. But the chances of that happening are, in my opinion, slim. Notre Dame could do it in football. Basketball, it seems to me, is quite a different sport.
I cast my lot with Gary Blair, who thinks UConn eventually will have problems getting all the top-notch out-of-conference games that it gets now, for several reasons, not the least of which is that its power record (whether RPI or other) will be dragged down by all those games against all those not-so-good teams, thereby making UConn a less attractive draw from a strength-of-schedule point of view. And with that change will come, again eventually, an erosion in UConn's ability to bring in the best of the recruits as it can now.
Will it ever get as bad as the decline at La Tech, where Blair worked? No, for several reasons. First, UConn has IMHO, the best coach in sports, period. That alone is a powerful draw. And when he retires, some day, he will leave a legacy, no matter who succeeds him. Unless something horrible happens, this is not like Pat at TN. This will be carrying on a true tradition, one that makes recruits proud to be on the team, even if Geno is not around.
Second, UConn is going to continue to have a terrific record, no matter who it plays, for years to come. Again, a powerful attraction. And third, a rising tide raises all boats, which in AAC terms means that UConn may (boy, do I hope!) make at least the mediocre teams more attractive and cause them to make a stronger commitment to WCBB.
Now, lots of things could cause this scenario to improve. The first is if UConn is accepted into one of the major leagues. Take your pick, makes no difference which. But if that's dependent on football you're looking at a long wait, even though the new football coach seems to be the real deal. Second, if a couple of AAC teams get their acts together -- develop themselves as, say, Louisville did -- the league looks a lot stronger and will be taken more seriously. Odds are against those things happening, but you can never say never.
I submit that pointing to a wonderfully successful recruiting class (or even two in a row) as proof that AAC affiliation means nothing is akin to claiming that two frigid winters in a row proves that global warming is bunk. The real answer to your question is "no number," because there is no magic number of five-star recruits that proves anything. If in 2020 UConn is still a top 3 power, still recruiting lots of top 10 recruits and competing as it does now, I guess I'd be convinced. But I believe that because this is long term, neither you nor I can make any claims with authority until the long term plays itself out.