There is very very little wrong with the structure of the SFS. Bugger all really.
Upgrade the catering etc, add Corp facilities, re-engineer the ends, put on a lid, by far the most expensive thing they can do.
The MCG upgraded the southern stand in 2011 for $55M
"The plan includes upgrades for food areas, concourses, toilets and improved entry and ticketing systems.
Viewing areas will be upgraded so that they are similar to the Northern Stand and there will be updated audio and visual equipment".
They also upgraded their wifi, put in another 800 tvs and the exterior lighting this year for 45m
It holds 45000 so it's equivalent in capacity to the SFS. Even if that costs you $100m now. The SFS just did the iptv, wifi screen upgrade so most of that money is off the table already. There is still $300m to do the other stuff.
You can stage the upgrade. So East and South first, then West and North, The stadium is still able to handle at least 80% of the events and you get an essentially new product.
This 55000 seater is a vanity project and a waste of money. For half the price you get a stadium that holds 10000 less, probably in terms of crowds more fit for purpose and completely up to date.