Way #3: Signing Poeltl would result in a needed frontcourt shakeup.
If San Antonio brings back Poeltl, it will probably result in a roster shakeup. On paper, the Spurs could have only a few roster spots available and may look to clear out some of that logjam. They would probably start in the frontcourt, with players such as Khem Birch being waived and Keita Bates-Diop and Gorgui Dieng not being re-signed, though they may bring back Sandro Mamukelashvili (Mamu). They may also look to trade Zach Collins rather than have him play a reduced role during the final year of his contract.
The Spurs could easily find a team interested in trading for Collins, which could result in them adding to their future pick total. Assuming that they would in that scenario, the Spurs would be left with Wembanyama, Poeltl, Sochan, Bassey, and Mamu as their front line. That may not seem like a lot of depth at power forward and center, but Wembanyama would primarily play the four, with some minutes coming at the five.
Meanwhile, Poeltl would play there full-time, Sochan would spend time at both positions, and Bassey and Mamu would likely get spot minutes at power forward and center, respectively. Those five players' combination of height, length, mobility, versatility, and switchability would make for a great big-man corps.