NBA isn't done for too long, because of the pandemic the games ended very late anyway, it is almost half of October right now, in just less than 2 months (or maybe just 3 months) we will be back again. The talks were about a potential Christmas return, but Adam Silver mentioned an early January return could be in play as well, plus the off-season is still going on, like draft will happen and trades will happen and free agency will happen so all in all I would say NBA will be back before we realize it was gone.
I know it is rarely ever anywhere, but if stake wants to keep NBA gamblers at bay, they could add "who will be number one pick" type of bets, and maybe check who is free agent this year and see who the big names are and ask "where will X go this year" type of bets as well until new season starts.