Let's level set here for a minute. First, NBCU must proceed with business as usual until the day SpinCo becomes a separate business. So, to that end, they proceed as normal in public while numerous plans and backup plans are crafted behind the scenes. For example, their NBA deal most likely included contingencies for how they would proceed if the USA network no longer existed. Remember, this is an 11-year contract, and cable has been contracting for a while, so it is highly unlikely this contract would have been signed without the ability to adjust programming platforms. It is probably happening sooner than anticipated, but cable will look much different 11 years from now, so both sides needed to carve out protection clauses in that contract.
In addition, I don't think the NBA is hyper-focused on cable. It has been reported that the NBA was particularly attracted to the NBC broadcast network and its ability to create a "Basketball Night in America" franchise. The broadcast component was why, in the NBA's view, Turner could never truly match NBC's offer since Turner didn't have a broadcast network.
The rights are with NBC Sports, not individual channels. And since NBC Sports stays with NBCU, the rights remain with NBCU. There is flexibility on the platforms airing content. Take the Olympics, for example. Ten years ago, NBCU put the Olympics on MSNBC to boost ratings for its struggling news channel. They aired the Olympics in the morning because Imus and their MorningLine programs were also-rans in the ratings department. Enter Morning Joe, and they decided it was more important not to interrupt regular MSNBC programming. So the Olympics moved to a different channel, and they didn't have to wait for a rights renewal to make that change.
Having said that, NBC doesn't have carte blanche to do whatever it wants without input from the sports owner. The broadcaster has some latitude as long as any changes provide the sport with equal or greater exposure. For example, NBC couldn't take NBA games off the broadcast network and move them all to Bravo without consulting with the NBA. In that hypothetical case, the NBA probably has some veto authority.
More information will be forthcoming regarding how this spin-off impacts NBC Sports. Perhaps SpinCo will sublicense content from NBC Sports, or perhaps NBC Sports will buy time on a SpinCo channel to air their content. Or maybe NBC decides to keep everything for themselves. Given how scripted content is going and the money they are spending on sports rights, they could put everything on the broadcast network and Peacock. Sports used to be exclusive to broadcast, so they might go back to the future regarding how they air sports.