Signing LaVine could more expensive than initially thought
While San Antonio would likely be a playoff team, they probably won't be a contender unless Johnson emerges as a third star. That’s possible, but that comes with salary cap issues. If signed, LaVine would make an average of $37.5 million a year; a massive amount that, when combined with other contracts, could result in the Spurs paying the luxury tax in the near future -- especially with Johnson potentially hitting restricted free agency (RFA) after next season.
Then Murray becomes an unrestricted free agent while Vassell hits restricted free agency in 2024. Johnson could make $25 million a season, Murray could earn more than Lavine, and Vassell, if he continues to improve, could command around $15-20 million a season.
Keeping all of them would be impossible, considering that just Murray, LaVine, and Johnson could combine to make an average of $102 million a year in the 2024-25 and 2025-26 seasons. It would make building around them extremely difficult, and even if the cap skyrockets, there's no way San Antonio can afford to pay out another $50 million to build out a decent roster around them.
Overall, the Spurs could clear out enough cap space to sign LaVine to a max four year, $149.3 million deal but the long-term cost may be too much. LaVine could fit nicely on the Spurs but the team's ceiling would likely be just a playoff team and not good enough to be a contender.
Johnson could still breakout in that scenario and give San Antonio a third All-Star, which would raise their ceiling, but then they'd eventually have to pay all three, and that would make for an extremely costly team. Therefore, pursuing LaVine in free agency would be a mistake.