Then Philly can pursue some other deal or run it back with Simmons and take their chances. Any good GM is looking at Philadelphia's situation right now and daring them to maintain the status quo. "Sure, go for it," they're thinking. Trot out the limited duo of Embiid/Simmons again next season, where their never-better-than-the-semi's squad gets to face-off against a healthy Nets team featuring Durant/Harden/Irving and a Giannis-led Milwaukee Bucks team riding high off their first Finals appearance (and potential championship victory).
And hey, if the Sixers' roster was instead the Kings' roster, then maybe I don't care too much if I'm a fan, and maybe I can play things safe and conservative if I'm the GM. After fifteen years of futility, near-relocation, bad luck, and worse management, I'd be happy to settle for playoff appearances and second-round exits every year. Just the hope of making it to the Finals would be enough for me as a fan, and incremental improvement might be enough for me as a GM, given the size of the market and the expectations.
But Daryl Morey isn't the GM of a small market team with modest expectations, nor does Philadelphia have the kind of fanbase that will accept less than a championship after enduring the Process. They are a title-or-bust franchise right now, and they have been for the last several years. If they want to laugh the Kings off the phone, then I would wish Daryl Morey the best of luck. See if you can get something better than one of the best volume three-point shooters in the league and strong, fungible assets you can flip for contributors. If he can, then he's as good a GM as everyone says he is. If he can't, well, then that's just the nature of the market in the modern NBA.