Modern rail seating prevents crowd surges and has been installed at many European stadiums.In Europe and UK the crowds are segregated. If you do what you are suggesting here, we'll end up with more crowd violence. Similar to what we had in the 1970s at our suburban grounds.
It's not going to happen.
Standing room areas have been kept small deliberately to prevent crowd surge. The larger standing areas promote a crushing effect. It is no coincidence that the UK has reduced standing to counter this effect. I lived in the U.K in 79/80 and followed Arsenal. If you were at the front of the North terrace when a goal was scored you could have your ribs broken against the fence as the crowd surged. The MCG Will not increase standing. Plus standing areas are predominantly the domain of men and thus this would also be seen as sexist.
From https://en.wikipedia.org/wiki/Safe_standing:
German clubs using rail seats include Werder Bremen, Hamburg SV, VfL Wolfsburg, Hannover 96, TSG 1899 Hoffenheim, VfB Stuttgart, Bayer Leverkusen and Borussia Dortmund.
In July 2016, Celtic formally unveiled their new 2,600 capacity rail seating area within Celtic Park, becoming the first British club to do so. The club had obtained a "safe standing" certificate 13 months earlier after years of negotiations with supporters, football authorities and Glasgow City Counci
Crowd violence in Australia is nothing like it used to be in Europe and the UK. In fact, in Europe and the UK it nothing like it used to be as well. That said, there are always idiots spoiling for a fight.