well the Teraleak did point towards
also, to jump in about Airveon here:
-1st the flying tera type evee just matches flying tera type Pikachu
-2nd its for Pokemon Day and balloons are often celebratory things
-3rd as limited as it is, flying tera type could have been chosen to cover Evee's fighting type weakness. GF either chooses tera types that will boost a Pokemon's type or counter a specific weakness. Again flying tera type Pikachu, while referencing past things also was just to cover Pikachu's ground weakness.
-4th gen 7 was going to have a flying type Eevelution but was scrapped. Being too close to a fan design.
the outcome is never never but the chances are low it means anything