The Marlins have new ownership now. And so many young players. They're a threat. The old teams also spent money, and then did teardowns. That's almost where the Phillies might be. I assume they will spend money when they are ready. We'll see if their GM is actually good. Still not sure if ownership is.
Nobody is completely untradeable. A-Rod got moved. Stanton got moved. Prince Fielder got moved. You just end up paying a lot of the salary. If Harper is truly untradeable, he'll also be unplayable, so it's kind of moot, the Phillies lose either way.
It will be up to Dombrowski to try and make this work somehow. On paper the half-rebuild half-compete model is hard to pull off, and hard to shed salary if the players are too old and expensive. Obviously also doesn't help that Kingery's contract is no less of an albatross than Segura's (but I don't think it's true that his option kicks in if he's traded. He may ask for that of course. He can also stop any trade. But I doubt anyone's picking that up).
I think you probably trade Hoskins, just to shake things up a little bit. Everyone else either has too little value or is still too important. Then you maybe move KIngery if nobody will take one of the other two middle IFs (though if you've traded Hoskins, you now have Segura and Didi as DH options too). Adding some Brad Millers or Kolten Wongs can be just as good if not better than adding another Cutch-type contract.
So for sure they can try to win in 2022 and maybe even 2023. I still think it will be grim at that point, and that a big reason the Phillies' rebuild failed is not just the scouting/development failures but that they did it 1-2 years too late and ended it 1-2 years early (in both cases with nothing to show for it but .500 teams). A full Marlins/Astros tank is obviously not an option but if there's no playoff spots over the next two years they are right back where they were in 2018 (and 2014), drafting high but not high enough, while only reaping modest trade returns on aged-out players (or in Nola's case, just a draft pick or rental return - unless they also repeat the Hamels pattern by re-signing him).