Nothing's official, even if Bill Simmons says that it's a done deal. I've been listening to many of his podcasts since his ESPN days, and sometimes he's been wrong about plenty of stuff. I'm not calling him a liar, but some of his thoughts comes from a "Bawwston" homer way of thinking.
That said, if NBC does indeed take the Turner portion of the package, I hope they can find a way for the Inside the NBA crew to stay together... whether it be them or Amazon using them for pre- and post-game coverage.
Meanwhile, ESPN will go through their usual shuffling of hosts and desk analysts, although their current lineup of Malika Andrews, Stephen A., Mike Wilbon, Kendrick Perkins and/or Bob Myers is actually a pretty good group compared to others from years past. Although, I would say that Myers doesn't have a lot of on-camera charisma (oddly enough, similar to Simmons, IMO), and Perkins can sometimes go off on some nonsensical tangents, but otherwise this group works well together.