Toronto's pick would also roll over to 2026 if it doesn't convey next year. So, the Spurs have three cracks at it before it moves to two SRP.
From a talent standpoint, there will certainly be a better field of prospects next year. But who's to say where that pick ends up? You balance out the chance that it never conveys vs. the chance that it conveys later in the draft vs the talent available wherever the pick ends up falling. It's obviously a crapshoot either way.
For the purposes of roster balance, it's better if it conveys now. Because if it doesn't, the Spurs could be looking at four FRP next draft. Barring trades they will for sure have their own and Atlanta's. Then possibly Toronto's (top 6 protected) and Chicago's (top 10 protected), plus 3 SRP. They are already facing a glut of young players who need time in the incubator, and not enough playing time and roster spots for them.
That was a long winded way to say, who the fuck knows? I have no faith in the this front office getting the draft right, so I think the more shots on goal they have, the better the chance is that they fall as backwards into a player. So, put me in the camp of it's better to convey this year, even with the shitty talent pool. They just have to get lucky on one guy, not the entire draft and being lucky is what this franchise does best.