Sanchez, Luzardo, Painter?
Wheeler's here for one more year - but he's too old to be part of a future core. If it's rebuild time, it would make sense to move him - he could return real value. Nola could be on the block, but given his current difficulties and the contract (four more years), probably not for a lot of future value.
Relievers? I have trouble thinking of relief pitchers as part of a "core." They're too unreliable, too variable year to year. Well, except Mariano Rivera, and... well, and nobody else, really. So none of them are long-term core pieces.
Catching? Short of High-A (Alirio Ferrebus), I don't see a catcher in the organization who can be part of the Phils' next serious "core." (And Ferrebus is certainly not a lock, either.) Anybody above Ferrebus could be moved for value.
Infield. Harper and Turner have FNTC, and contracts that extend until sometime in the next millenium (OK, I exaggerate!). They're likely to be here, unless things get so bad they actively ask to be traded. Turner will need to move to a less demanding defensive position. Bohm is a FA this winter; he's gone. Stott? One more year of arbitration, then FA, unless he's extended. Is he worth a long-term extension?
In the OF... Marsh has one more arbitration year, then FA. Same as Stott; is he worth a multi-year extension? Other than that? Crawford is so young that he might grow into something of real value. I doubt that Rincones will.
Then Kyle Schwarber. Four years, at $30k. I'd probably keep him around, as the DH. But that's not critical; in some scenarios, it might make sense to trade him (no FNTC) and move Harper to DH (assuming they obtain a better hitter for 1B).
Bench players are, by definition, not part of a core.
After that...some of the prospects on the top of everybody's lists are as likely as anybody, if they develop well. Too soon to know - but I wouldn't trade them for a 2026 band-aid.