Add some extra complications like different tax systems across the continent, unsustainable ownership models across different teams (where one guy pours money, or a country, or one big sponsor), overall lack of responsible finance planning (examples of AEK, Monaco, etc) and you get a very complicated landscape.
Additionally, for example Serbian teams or even Greek teams are great for the league, its entertaining to watch, but because of economic power of the country, tv deal value there is extremely low. Yes, they compensate this with social media activites and so on, but this time of benefit it is harder to quantify.
Add, countries like France or Germany where basketball is still very niche product and falls far behind football/soccer. Or the fact that most clubs do not own their arenas so they can not claim most of the matchday revenue. Challenges with local championship and scheduling issues - in Spain they play very good teams week in and out, in Lithuania Zalgiris is on 33 win in a row series.
In addition, add FIBA messing with national team windows, or creating their own competition with unfair incentives (money for participation and so on, clubs leave BCL as soon as these incentives expire), players playing 80-90 games a season, coaches who want you to practice.
My point is that this is entirely different beast than NBA. I think before NBA comes into play, European basketball needs to decide what they want and be unanimous in this. We can not have teams like Real Madrid holding out til last second to sign Euroleague deal, or teams voting against each other because of the political/rivalry/history things. Hopefully, this can be sorted