It's a possibility. From what I've seen, they can actually do it.
However, there are a lot of moving parts in deals like that.
The Spurs were one of the first team's to evaluate personalities and focus on the mental part of the game. I don't think they would be interested in Fultz for that reason. They may like Saric, but he's not enough in a trade for Leonard.
Maybe Covington, Saric, and draft picks would be enough to get it done, but I doubt that is the best offer the Spurs would get for Leonard.
As far as George goes, he is an LA kid who wants to be back in LA. He might go somewhere else, but I doubt it.
Technically it's possible. It's not like the "writing is one the wall" though.