What happens if an ACADEMY team wins ascension?

nope
theres basically 2 systems that allow t1 teams to have a team in t2

Partner team (independent org) -> they ascend and partnership is ended
Academy -> they cant go to ascension and the runner up takes their slot

We recently announced that in 2025 partner teams are able to run Academy teams in Challengers to help develop new talent for their rosters and provide more opportunities for players. While Academy teams will not be eligible to qualify for Ascension, we are excited to increase support for the Challengers ecosystem. Keep an eye out for up and coming players on the below Academy teams across the globe!

Heavily implies that that’s not true