This hasn't ended up going so well. Queens Square filled to capacity according to H&S last Saturday for the England vs. USA Match, with about an hour to go they stopped allowing people in. Many of those outside didn't take this well and parts of the fence were damaged.
Meanwhile inside, there was only one bar open which ran out of almost everything including pint glasses, there were reports of some trouble and drunken behaviour.
Now all England matches will be ticket only and there will be a ban on all alcohol, although they're removing all the fencing to make better use of the space, it's hard to see how they will police this both in terms of numbers and people drinking.
Edit to add:
BBC Bristol Link