Urriak Uruk
Gaming is fun, and fun is for everyone
I'll admit it is tenuous, and quite possibly wrong: but a Strixhaven Setting book is the most plausible hypothesis for a book that would combine the decidedly odd Draconic Monk and Ranger Subclasses with the equally odd Fay Lineages, which do seem to be connected. No Monster book has had Subclasses, and the only books other than the PHB/DMG that have both Subclasses and Lineages are Setting books. The flavor for both UA is...odd...and they do seem to be for the same product, based on timing.
One way or another, whatever this is seems to be a break from precedent...another WotC specialty.
I mean, I could be maybe convinced the fey stuff is renamed things actually meant for Strixhaven... but that the Dragon subclasses are also for Strixhaven seems like an even bigger leap. I know each dean of the Strixhaven schools is a dragon, but that's a very big jump to assuming that the subclasses fit that setting, which they definitely do not.
So here are the arguments I'll make against Strixhaven;
1. It is brand new for MtG, unlike both Ravnica and Theros (which have had multiple sets and are established popular planes).
2. Strixhaven has a weak tie to dragons, and beyond having Elder Dragons is not dragon-themed.
3. Besides owlfolk, there is no evidence the other Fey subraces exist in Strixhaven (including renamed boggarts). Strixhaven is also more "Hogwarts Magic School" themed than Fey-themed.
4. If this release is in July, this would be back-to-back releases of settings, which would be unusual for two mainline WotC releases (I do not consider Wildemount a minaline release as it was made mostly by non-WotC writers).
Overall, I find that people have seen that Owlfolk are in Strixhaven and are jumping at the coincidence. Owlfolk in Strixhaven makes sense; there is a perceptions owls are "wise" and it is a plane entirely based around a school. Beyond that however, there is almost nothing connecting these subclasses to that plane, and people are overestimating the chance of WotC demanding cross-promotion.