They won't trade him, b/c at the end of the day, it's much better to have have a top-5 talent in the NBA than not, and by definition there are only 5 of those. It's better to have/sell hope of winning a title, and as long as they have Embiid, there's hope.
As far as their chances of winning a title, it has to start with constructing a roster where the pieces can mesh with Embiid but can also produce some offense while he's sitting. The odds of him being able to carry a team 44-min a game Brunson-style has to be filed under "ship has sailed" territory with his history and age. The real problem is that Maxey isn't quite good enough for what they need him to be— he's great with Embiid but the offense mostly stagnates when he's the primary option. So, do you try to add a big third banana (Paul George), improve around the margins, or try to upgrade the Maxey "second option" spot? Far-fetched, but: I would be interested in trying to deal Maxey and draft capital for Devin Booker, if Phoenix concludes they're stuck in a dead end.
Edit: regarding the "loser" topic: he's not a loser obviously. But I do think it's fair to say that in addition to the question marks around his health and conditioning, this postseason has raised (or re-raised) legitimate questions about his composure and leadership. From the flagrant fouls to the weird behavior at the end of last game... it's another reason to doubt whether he can shoulder the huge load that winning a title would require with the current roster.
Edit2: oof, I forgot what a salary difference there is between Maxey and Booker. But, dealing Maxey for a better, older, more expensive player makes sense to me in principle given where Embiid is in his career.
