We already have a standing area at the back of the Kop
Sheffield is similar to Sunderland. Similar percentage of fans-to-population attend the game. When you consider the pigs attendances, there's 55K attending football in this city
Everton is a prime example of what/where we could be if we were able to sustain top flight status.
Liverpool is a smaller city than Sheffield and Everton are the smaller club, starved of recent success, but still building a 53K stadium.
I realise they were a successful club back in the day, but have done nothing for 30-odd years.
It's top flight football that has maintained a chunk of their fanbase.