Typical "

Aldridge ball isn't winning ball

" take. The Spurs had eight players who switched between SG, SF and PF this year, and that's not including Forbes, Murray or LMA. Kawhi and his 30-plus mpg were missing, which made it look like wing depth was a problem. I've nothing against the idea of letting go of guys like Bryn and getting bigger dudes in there, or the idea of moving on from guys who can't shoot and getting guys who can. But ultimately, the lack of bigs hurt the team more, and it could have been even worse had LMA not been such an iron man.
You've continued to erroneously paint me as this traditionalist, anti-analytics guy, and I'll resist refuting that again for the sake of not derailing the thread. However, the team is going to play big from time to time to maximize their advantage, so strictly counting on three bigs isn't going to work, especially seeing as the top two are getting up there in age. That's also ignoring that Joff could well opt out of a min deal and Costello may not have to take a two-way deal again. Getting a) Fresh blood to groom for Pau's rotation spot in 2019 and b) a big who can play with the bench better than Joff is important. None of the "modern" NBA teams have shied away from bolstering their front courts recently. The Spurs would be dumb to not do the same.
There's a good chance that the team returns six of the eight "middle guys", which Manu and one of Bertans/Forbes being the only likely departures.
Manu doesn't have an option, as far as I know. So if he plays next year, it will essentially be for free. That's why I don't think he'll be back. Blossom will fill one of those spots, and Porter/whatever big they draft will fill the other. So they're really looking at hoping one of Green/Anderson/the other of the Forbes-Bertans pair having to leave to get anyone else. That could happen, but even if it does, there's no reason to believe it has to be anyone special. There's always a pretty large number of those guys who end up in the d-league or at low-salary guys.
I agree with DPG that they'll be looking for overall talent more than just a position. But they'll need to build a roster both for next year and the future. When I look at current fits next to LMA and long-term fits with Murray and White, I see guys like Williams and Porter far and away better choices.