it'd be a smart move for them to see if there's someone out there that'd be a better fit next to Embiid and Butler. Could probably get a couple of really good players for him while his hype is still high --> probably a starting-quality PG that can hit from outside and pass as well as a good forward 3/4 type that can hit from outside and rebound. not sure who that team and players would be right now but I think Simmons could fetch a nice collection of assets in a deal.
Ball is an injured significantly lesser player than Simmons. Kuzma is what he is at this point (given his age and his relative lack of growth). If they were to trade Simmons they would do far better than Ball and Kuzma.
I think it's going to be tough to trade Simmons right now. Not because he's not a great talent, but because of his contract situation. Nobody wants to trade into a Pelicans Anthony Davis situation.
One year left on his rookie contract, eligible for a max extension this summer. Klutch client, buddies with LeBron,
already claimed that he'll play for the Lakers (while at LSU), and
the NBA already investigated Lakers for potentially tampering with Simmons this year (wanting to work out with Magic).
Then there's other things like the LSU situation/Showtime documentary (where he solely looked out for himself), the recent comments about Philly fans, I don't know if this is a guy a lot of teams would be confident is going to commit to their team and be that superstar the fans/city will rally around. "I want to play in this city my whole career, and these are the greatest fans in the world!" You're not getting that from Simmons, now you're not really getting it from Kawhi either, talents trumps all, just think it makes a team less willing to give up a lot to get him right now.
Of course all that changes if a team can discuss an extension with Simmons/Klutch before a trade, but then I think that hurts Philly's position by openly letting it be known they're shopping Simmons. Simmons can say he won't sign an extension, and at the same time this alienates him against Philly if they can't find a good trade and decide to keep him. Philly could sign Simmons to an extension first, but that wasn't a good look for the Clippers when they did it with Blake Griffin.
Now a little less risky for teams trading for Simmons because you have 5th year restricted free agency if Simmons doesn't want to sign, though I wouldn't put it past Klutch to have the first player who tries to strong arm or maneuver out of restricted free agency when getting max contract offers.
I think it's tough to trade Simmons right now. Not really sure what the haul would be.