Tas Uni report a 14% increase in domestic student enrolments for 2021. Local & a large increase in interstate enrolmentsIt also says most of those young people are foreign students - temporary arrivals that in reality have no impact on the viability of a Tasmanian AFL team.
The reality is that Tassie has the highest median age in the country, and over the last 20 years it's blown out from 36 to 42. The national median age is currently 37. I wouldn't use a demographic argument if you're trying to justify a Tassie team.
Melbourne is projected to have 400k less people than originally forecast by the end of 2022.
The 0-14 age group in Tasmania not much different to Victoria. Its something like 17.7% to 18.2%. So not a lot.