Without DeRozan, the Spurs aren't sending Kawhi to Toronto. Same with Boston and either Brown or Tatum. I just don't see Buford and Pop wanting a hodgepodge 5-6 player package without a star or future star included in the package. Spurs were very good last year without Kawhi. Their thinking in trading him is to get another star or future star, add that player to the current roster and compete.
OG is probably the most interesting prospect that has come up in trade rumors that is not named Brown or Tatum. I'd take OG before Fultz and Saric. This kid is the exact type of player than can stay on the court in the playoffs and make a difference. Imagine a Murray-Walker-OG lineup defensively.
IF you include Siakim, who is basically a younger Mbouh a Moute, in the deal, it makes it even sweeter. Powell, who would have to be included for salary reasons, has had some good moments too and is pretty versatile.
Then, if you include firsts in 2020 and 2022, there is a chance that the Raptors implode before then with Leonard leaving and Lowry fading in effectiveness. Those picks could be really good.
On top of that, the Raptors have a trade exemption that could absorb all of Danny Green's contract, which frees the Spurs to pursue the youth movement.