The NBL and other international leagues have a huge advantage in that the draftees are playing in an open league. I believe over time teams will prefer players who have proven themselves in these leagues ahead of college... but it's up to the NBL to prove this by producing NBA level next stars who can contribute from the outset

The main issue with playing in europe or Australia is being able to gauge the level of each league which can sometimes change. With college, scouts feel like they have a good understanding of where the level is and the key differences between it and the NBA making it easier to assess (in theory).

I agree that for player development, playing in pro leagues against adults is probably better in theory, but at the same time, these colleges know what it takes to get their guys noticed and drafted higher and some have far more money and resources for coaching and development than any non NBA pro team world wide.

I don't see any significant change to top or even mid tier prospects playing overseas. In fact I think overall fewer will go pro early with NIL available.

College hoops is also something that a lot of players have a genuine love for and having that college experience is seen as a positive.

Even quite a few Aussie kids are heading to college for just a year or two, then coming back for development player deals.
Could be a few factors, cash, lack of playing time or combination that they could make a roster here, get some pocket money (comparable to a full or part time job) and try and get a few contracts. Or even simply just a bit of being homesick.
There are some that have unrealistic expectations, that they'll star, get plenty of minutes then have NBL deals lined up when they get back. But mostly freshmen will sit and with the transfer portal, teams can grab a more experienced player especially from a smaller school rather than invest with young kids. Then they hope those young kids get bad advice, enter the portal themselves and find no-one wants them and find another high school kid to replace them and the process starts again.
AAU seems to have ruined junior basketball in America, play more games and tournaments than train. Now they're working out that overseas kids, especially European are dominating the NBA, more through skill than physical gifts. I wonder how long before high level American kids will start going to European clubs, rather than the other way around. And I'm talking about 14 year Olds. But AAU pays too much and all the hype will keep them there. But imagine if someone like Flowers had gone to Europe 5 years ago, had all the cockiness (not that he's the worse by any stretch) beaten out of him by some Spanish coach that didn't give a shit, and was taught team fundamentals, instead of a crash course in that crossover between juniors and professionals.

I think one thing that makes college still less attractive for internationals is there is a visa issue which prevents them from accepting NIL? IE the visa they get to play college ball doesnt allow it. I might be wrong on that, but again that makes it more likely high profile internationals are better off staying OS and playing pro.

I think the US college system is the best for a player's development at that age, however the NBL Next Stars program has done very well given the previous graduates places in the pro basketball, and to a lesser extent, the amount of Next Stars kids you see on current NBA mock drafts. Next Stars is obviously biased though to be better for young men who can physically compete with older men.

I honestly don't feel like the US college system is the best development program at all. A professional style system where you don't have to pretend to be a student athlete is best for top-level prospects IMO. Even with payments etc being the norm, I feel like the Next Stars program and others like it have a place even with these changes to the college system.