In this trade, the Lakers get Kyrie and other assets, the Knicks fulfill their goal to acquire Kevin Durant, the Nets get several solid players that they can build around along with 9(!) first round picks, while the Spurs take on Westbrook's contract.

Why the Nets do it: This is the best offer that the Nets will get for Kevin Durant. 8 first round picks along with several young-ish assets as well as older roleplayers to fill in the gaps leaves the Nets as a young playoff team around Simmons, Randle and Barrett with all of the roleplayers to be an actually solid team. This is also likely the best offer they will get for Kyrie. Not only do they get the first round pick, but also several roleplayers whose combined value is worth quite a bit more than Westbrook. This builds a young team despite mistakes of the former front office in trading away picks. Brooklyn's done this before, with the KG/Pierce trade into the era immediately before the KD era, and they can do it again.

Why the Lakers do it: They fulfill LeBron's reported demand of acquiring Kyrie Irving which has been reported to be offered alongside Harris for both picks which the Lakers don't love. However, in this trade they also acquire great defensive center Jakob Poeltl, allowing AD to play his preferred Power Forward position, and just being another solid player that may push the offer over the line of being worth both of the picks.

Why the Spurs do it: The Spurs continue the tank by trading away several older roleplayers and getting back Westbrook and a first round pick, which could be viewed as an asset to be used with the Spurs' pick if it does not win the lottery to move up toward acquiring Victor Wembanyama. Westbrook's contract is also expiring so it is not a long term money hit either.

Why the Knicks do it: The Knicks finally become relevant again, even if it is at a sacrifice of eight first round picks. Their main target in free agency in 2019, Kevin Durant, is finally attainable. He is surrounded by players that the Knicks have proven with large contracts that they trust, in Jalen Brunson and Mitchell Robinson, while still retaining Quickley among others. Even if this may not be the right move for the Knicks, all signs point that they would accept this trade, to acquire KD and hopefully contend.

In conclusion, this trade has a massive leaguewide impact, from LeBron and AD's happiness, to the Lakers entering contention, to the Knicks entering contention, to the Victor Wembanyama sweepstakes, and the formation of a new solid young team in Brooklyn.