I might be completely missing the point (and probably I'm also being gullible believing ads and also that the series would stick to it), but I have been pondering about something: what reveal can happen that Adrien does get to keep the knowledge of without threatening the status quo and such? At this point I believe that his nature as a Senti being is the one thing that would make sense. You know because it would be an internal revea; that now he knows an extra something about himself alongside those that know already. But that doesn't mean it affects how his dynamics are outside or that, or affect how he is perceived as Cat Noir. In short: it would be a monumental reveal for him personally, but it doesn't shake that which is established... So yeah it's like the perfect thing to keep the big secret revealed tease without doing the routinely Bunnix, Viperon, and now even himself erasure to keep the status quo from changing.
I might be completely wrong. Regardless I leave this here as my theory for the season 6 finale.
