AROUND the NBA:

[F Gump]

Brian Windhorst: "He owned 27%, and now they own Ramona about 77%; is that correct?
Shelburne: That the Buss family owns 17 or 18…
Windhorst: And Patrick Soon-Shiong owns about 7%. We don't know, unless you do, what percentage is selling.
Shelburne: I believe they're buying all of Mark's shares.
Windhorst: It's not; he didn't actually make two billion because he didn't pay 10 billion for the team. But I'm not going to get into all that; it has to do with valuations. There are potentially reasons why he would want to get liquidity for his businesses. Again, this is not a financial podcast. And there are also reasons why he would want to potentially be able to show the SEC that he made an investment that returned a big profit for his insurance business."

One note about the background to this deal -- it would seem that Iger/Kushner were looking, and got word that the Lakers (Walter) were open to a sale. So Walter's existing woes likely had everything to do with this happening.

Some notes about the financial aspect of this deal...
1 As you noted, this is not a sale of 100% of the Lakers, but rather a portion, so the valuation increase ("profit") will not be as eye-popping as it has been trumpeted. But the NBA and its 29 other owners will eagerly embrace and use the packaging that LA is being sold for 12.5B and team values are spiraling. And even though it's not 100%, it will still net a very sizable profit that seems likely to exceed 1B.
2 The sale may have been agreed to already, but it won't close for a while, for 2 reasons:
...a. NBA will have to approve, which takes some time -- maybe not a huge delay, since they already know these prospective buyers, but they will have to schedule a meeting, do due diligence, etc etc. Even with a slam dunk deal, since they all have so much at risk, the other owners will look carefully under the hood before accepting the new partner. 
...b. Walter will also delay for a length of time to ensure that the sale does not happen until it's at least a year and a day since he bought this. The tax man will want his cut of the profits, and making it a "long term" ownership being sold is wise from that end of things, cutting the tax liability about in half.