That could prove difficult considering both players were useful this season and project to be better next season. However, if the Spurs were to bring both back, they'd have to find a way to keep and utilize both players.
During the second half of the season, San Antonio attempted to do just that by dabbling with two-big-man lineups. The Collins-Landale pairing had a -3.1 net rating while lineups that included both players struggled to score.
Landale, on the other hand, was part of a successful pairing with fellow center Jakob Poeltl that had a superb 8.9 net rating. That suggests that Landale could earn spot minutes at power forward, increasing his value to the Spurs, whereas Collins may be best served playing at center.
Although playing behind Poeltl limits Collins' role, he has the highest offensive ceiling of the team's center rotation and was very productive overall. In fact, despite missing nearly a year and a half of basketball, he averaged a solid 7.8 points, 5.5 rebounds, and 2.2 assists in only 17.9 minutes. He even displayed the ability to space the floor, knocking down 34.1% of his threes.
Zach Collins has the edge if one must go
All of that hints at big things for Collins, who was always known as a talented player but washed out in Portland due to injuries. With another year in San Antonio and being able to enter a season healthy, Collins could establish himself as one of the league's best backup centers and provide an offensive counter to Poeltl.
Landale doesn't have the same ceiling as Collins but he's a better shooter, even if he has yet to show it for the Spurs. He shot just 32.4% from three this season but he connected on 37.3% of his threes in international play prior to joining the Silver and Black.
San Antonio could definitely use that version of Landale, but with multiple picks and Lonnie Walker's restricted free agency looming, a lot is still up in the air. I expect San Antonio to use three of their picks, re-sign Walker and waive Langford, which would put them right at 15 players, including Landale.
However, that assumes the Spurs don't sign anyone else in free agency, and with significant cap space, it's hard to believe they wouldn't sign at least one player. The Spurs could also select a center in the 2022 NBA Draft, placing him fourth in the center rotation. In any case, unless something unexpected happens, such as a trade or Walker not being re-signed, Landale may not return next season.
Overall, given roster constraints, San Antonio will likely have to make a decision between Collins and Landale. Despite Landale's shooting ability, Collins has the highest upside of the two players. Factor in the draft and free agency, and it's likely that there won't be enough room on the Spurs for both.