I worry about this. The Eagles currently have a long waiting list for seated memberships. I'm pretty sure we're sitting on about 60K members of all types at the moment. The dockers are probably pretty close behind. It looks like there is still going to be a waiting list for seats. Make it 70 000 at least while it's being built, rather than modifying it in a few years' time.
Port and Crows both have 60,000 members. AO capacity is 53,500. In a 60,000 seat stadium you could sell 50,000 11 game memberships, which would be significantly higher than anybody in the league currently. West Coast might be able to do it, not sure Freo could.