I was thinking more of another Boston area AM/translator combo either failing or (unlikely) deciding that its translator was too expensive to keep. Could, say, the WRCA translator be transferred to WMEX if the price is right and if arcane FCC rules don't force WRCA to continue pouring money into that black hole for several more years?
I'm a little late getting back here to reply (it's a busy time with consulting clients), but here's the basic answer to this question: it depends!
More specifically: it all depends on which license category a translator falls into. You have some translators that were never locked to an AM station - when the FCC first began allowing AM stations to be rebroadcast on FM translators, station owners were free to go out and buy existing translators (or repurpose translators they already owned) and use them to relay their AMs. Those translators were free to be sold or repurposed at any time, whether to rebroadcast a different AM or an FM or an HD sub.
Next, you had translators that were granted in the two "250-mile" windows, under which existing translators could be purchased and moved up to 250 miles to be used to rebroadcast AM stations. Translators that were moved in those windows ended up with temporary license conditions binding them to be used only to rebroadcast the specific AM for which they were moved, for a period of four years of actual operation from the time they were licensed at their new locations. (The one I can speak to very specifically here is the one I moved, Bob Bittner's 101.3 for WJIB, which we moved south from its former location in Maine. Up there, it had been an "unlocked" translator - he bought it and paired it with WJTO, but could have sold or moved it at any time. Once it moved to Boston, it was locked to WJIB for four years, not that it's going to be sold off separately now.)
Many of those translators that were granted in the 250-mile windows are now at or approaching that four-year limit and thus could be resold now.
The final category (for now) are the new translator CPs that were granted in the final set of windows in 2018. Those were permanently locked to their parent AMs and cannot be moved to a different primary station or sold separately from their AM parent.
If you know the dates of each window, you can look through the original CP applications for a translator and figure out which category it's in - or you can look at the actual license authorization and see whether either the four-year or permanent lock to the AM parent is listed as a condition of the license.
And with my broker hat on - yes, there's a definite difference in the market value of each category of translator. All other factors being equal (signal, tower lease issues, the general push-pull of supply and demand), an "unlocked" translator that has more flexibility to be fed from an FM HD or to be moved to a different AM parent is always going to have more value to a buyer than a translator that's permanently locked to an AM, with all the baggage that an AM station brings to the table in 2021 and beyond.