Look, Shelly Sterling is not the good guy. She's up to her shoulder-pads in court-sworn evidence from discrimination lawsuits, near as much as Donald. But this is an O.G. move. According to ESPN, Donald Sterling's estranged wife has agreed to indemnify the league from any lawsuits, including those from Donald, related to the $2 billion offer from Steve Ballmer that the Sterling Family Trust accepted.
The indemnification is actually part of the sale to Ballmer, since it is technically still being carried out at gunpoint, and includes an agreement to not sue the league on behalf of Shelly Sterling and the trust. The indemnity means, essentially, that the trust will secure the league against anything that happens in a suit. This will help move the deal forward on both sides, but it's an especially big win for the NBA. It is sort of a crazy move on the part of the trust, but it seems like Shelly just wants to push this thing through at all costs; this ensures Shelly's going to get paid. Still, a deal like this represents a sizable bet against Donald on the part of the Trust.
That said, as plenty of smart folks like Michael McCann and others on Sports Law Twitter are already pointing out, though, how much this means depends on the scope of the indemnity agreement. This likely covers the sale of the team, and so forth, but Sterling's also made motions that he might even go after the NBA via anti-trust laws and breach of his constitutional rights, which are totally separate things.