Yeah, supporters are segregated at soccer matches over here, and it can lead to a really tribal and aggressive atmosphere with law enforcement everywhere. I'm just back from Charlotte and Atlanta, and thought the mixing of supporters was a breath of fresh air, and I'd hate to see the NFL lose that. The NFL London games with all 32 jerseys on display is a brilliant atmosphere too.
Sadly, there will always be ar5eholes that will spoil anything, and you're right that alcohol (or bevvy, as we call it here in Glasgow) is a huge aggravating factor. You can't have alcohol at a soccer match in Scotland, and I doubt we'll ever get it back (41 years now). Too many eejits (another good Glasgow word) that can't behave ruin it for the rest of us.