As for a possible resurrection of the CD format, I've been reading about how cassettes are hot now. I kind of get SOME of the reasons why, but who would have ever thought the 'compact cassette' would still be viable in 2021 ? This gives me reason to think that CD's will also return from the dead brink of death.
I don't think it is likely, but your guess is as good as anyone's. Aside from the sonic issue (which when it was a new format was remarkable), CDs no longer have that advantage over what is readily out there--I mean downloaded files. In fact, for anyone that cares, downloaded files can easily be had in so-called Hi Res formats which have at least a marketing advantage over standard CD.
CD is simply a black box. You stick it in the slot, and music comes out. The CD format had at one time a major convenience factor (but little if any visual-aesthetic appeal). In fact, with few exceptions, CD players always looked like the black boxes they were. And the new ones don't even have the nice displays of the older models. From that standpoint, one might as well have a black box serving unlimited files, which is even more convenient and practical than a dedicated CD player.
Alternately, the record 'revival'... Records and their players possess a visual-kinetic aesthetic not present with either CDs or files. You can watch something spin around and fiddle with adjustments, change cartridges and so forth. You can hold an album cover in your hand and actually read the liner notes. You might get a poster or some other marketing insert to sweeten the deal. You might be able to learn to ignore the pops and ticks, or even to consider that a feature.
Cassettes have (or at least once had) a convenience factor. It's what you needed for your car, for your own mix. Will cassettes 'come back'? On a long term basis? Like records? No one needs that for their car anymore. The home? Possible production of a high-end top tier cassette deck is doable, but a stretch. Where is the tooling? That would likely have to be recast from the ground up. It's not like Nakamichi, Tandberg, ReVox et al have ready parts in a warehouse, just waiting for the call to assemble. It's not like Nakamichi, Tandberg, ReVox can even be called.
The old high-end decks (along with the mid-fi models) are wearing out, and replacement parts plus the skill to work on them are scarce (if you can even find a part and locate someone to work on them). The idea that you 'just need to change the belt' on a forty year old quartz locked logic controlled tape deck, and then you'll have something with factory specs that will last another forty years, is wishful. Cast metal frames will be intact, but once the plastic/rubber parts start to go where will you find replacements? From another forty year old deck? Good luck finding tape heads.
Is anyone making metal bias tapes (the ones that sounded best) anymore? Dolby Labs no longer licenses their NR for cassette media (which some claim is a good thing from a sonic perspective--I won't argue that), so you can forget about much in the way of high end S/N.
Go to Yoo Toob and search for xraytonyb's channel. He's spent the last month running down a Pioneer CT-F 1250, the last of the 'silver' top of the line Pioneers. So far he's completed six episodes on the deck. Very interesting tear down and refurb. Then ask yourself whether you really want to get involved in the format.