The Spurs could be back in contention before we know it
The Spurs, on the other hand, are on the rise and could even be a contender in a couple of seasons if they play their cards right. They have Murray, a former teammate of Leonard, who just made his first All-Star team and has the potential to get even better. They also have a bunch of promising prospects like Johnson, Joshua Primo, and Devin Vassell, any of whom could break out in the next couple of seasons.
Not only that, but they've added plenty of assets, including 3 1st round picks in the 2022 NBA Draft, a 2025 first from the Bulls, and several seconds. Those assets aren't going to keep Leonard up at night, but it's a case in point as to why he should've trusted the Spurs.
San Antonio has made several incredibly smart trades that have put them in the position to get better fast. That could start at the draft where they may have three top-20 picks and could possibly trade up into the top three and draft another star. Or they could keep their own pick and instead try to acquire another lottery pick by packaging Boston and Toronto's firsts together.
No matter what they do, San Antonio has an excellent track record of finding talent in the draft (including Leonard). Therefore, they're likely to come away with at least a couple of talented young players that they can potentially mold into stars.
The Rebuild wouldn't have been necessary if Kawhi stuck around
Had Leonard stayed, San Antonio would've still had Murray, who showed plenty of promise even then. Moreover, they probably wouldn't have traded Derrick White, and they had already drafted Lonnie Walker prior to dealing Leonard.
San Antonio could've even drafted Johnson 29th, but with their own pick, instead of Luka Samanic. That means that the Spurs could've had a core of Murray, Leonard, Walker, Johnson, and White. Imagine a hypothetical Murray, White Johnson, Leonard, and "insert center here" lineup. What could have been? Unfortunately, we'll never know.
Fortunately, Murray is much younger, has plenty of talent, and actually wants to play in San Antonio. Thus, the Spurs are much better off without Leonard, while the same may not be said for Leonard going forward.
Ultimately, the Spurs don't miss or need Leonard at this point in their progression. Still, he hurt his legacy by forcing his way out of San Antonio, as well as permanently damaging the relationship with the team that drafted and developed him. All of that just to play in L.A. with another star, and it clearly hasn't gone how he might've expected. That feels like karma.
As for the Spurs, it took them several seasons to realize that they needed to rebuild but they've done an excellent job thus far. Also, they've amassed an impressive haul of assets, which will allow the team to quickly retool around their new star, Murray.
They'd have done the same with Leonard but weren't given the opportunity, now, they are proving him wrong.