I don't think there's a hope in hell of significantly improving the atmosphere.
1. Huge chunks of the stadium are given over to corporates, who might as well be stiffs for all the noise they generate. Like the old Main Stand at Maine Road, only more so.
2. High prices keep out many of the traditional 'lads' and if/when they do go they are split up into small pockets by the reserved seating arrangements. Yes, OK, there is the odd cheap game, but when the habit is lost people tend not to go at all.
3. The attitude of the stewards and many of the crowd to anyone who gets 'excited'. Many people swear when they get emotional. I know in an ideal world they shouldn't but they do. The 'policing' of the stands, for want of a better word, means that some don't go and others stay quiet.
I don't see any of these factors changing, ever. It's the price the game has paid for turning football into something more like ballet or theatre, designed for the well-heeled middle classes and 'families'. City now clearly favour the corporate and family sectors, and other fans are only allowed in as long as they don't upset these groups, and as long as there's still room in the ground not needed for them. The reason is money. The corporates and families spend most.