As far as I can see (in all .w2scene and .w2phase files), the only place where it is used is the conversation with Boris the Troll - if any imported fact from TW2 exists, then the player is rewarded with the head of an elf, with a reference to another troll in the previous game (
"Elfies good. Like tometooo."). The same applies to import_geralt_rescued_triss, but import_council_exists (which depends on the same choice) has a few minor consequences related to Carduin and the Conclave of Mages. Anais is not even mentioned in the game outside the conversation with Voorhis when simulating an imported save. import_odrin_met seems to be unused in the files I checked.
Perhaps there will be another expansion (not this year, though), while it seems unlikely at the moment, in
this recently released strategy document there are plans to significantly expand the studio and for additional media content and product lines for the core franchises, and also further active marketing and support of the earlier releases. Maybe if TW3 and the currently planned two expansions sell better and for longer than expected, a third expansion becomes viable.
What happens after Cyberpunk could also depend on how that game sells, but with the planned expansion of CDPR, they might be able to develop games or expansions for both franchises at the same time. On the other hand, if more Witcher games were to be made, it is rather likely that they will again have poor save import. At best with a new protagonist and supporting characters the choices in TW3 will simply not be relevant to the new story.