I thought Tasha's was supposed to be forward compatible?
Three things are true:
1. The new PHB has guidance for how to smooth out the rough edges of compatibility with older subclasses, so theoretically, ANY 2014-2023 subclass can be compatible with a 2024 class, with some small adjustments (i.e. moving a subclass feature to a new level, or dealing with the fact that a subclass feature is now redundant with a standard class feature, etc.).
2. They felt that the Tasha's subclasses didn't require as much work to rebalance or streamline (at least, those that they considered pulling forward into the PHB. This would probably not be said of the Twilight cleric). This suggests that certain patterns that emerged in Tasha's subclasses - setting some features to PB uses, for example - as well as those that emerged earlier - giving sorcerer subclasses bonus spells, for example - were going to become standard in the new PHB.
3. They ended up changing nearly every subclass, including some that came from Tasha's, with small changes, if they brought them into the new PHB.
Despite all of that, I expect to see a new book that reprints, with small changes, lots of old subclasses, and a few new ones; lots of old feats, and a few new ones; and lots of old magic items, and a few new ones. That does the trick of giving stuff for both players and DMs, justifying the purchase beyond "this is just errata", getting this re-release book out of the way instead of dragging it on for ten years, and making sure there is a book in print that has all these options. I could be wrong, it's just a prediction!