It would only be the same as most other major venues e.g. Wembley, AO Arena etc.
The seat issue doesn't matter as they will either already be sold out, so you'd be trying to sit in someone else's seat which you don't have a ticket for, OR it wouldn't really matter anyway from a crowd control perspective as the seat isn't occupied.
The hospitality areas will be closed off so there's no issue from people trying to get into those without the relevant ticket.
In terms of the concourses, human dynamics suggest that people aren't just going to queue at a handful of overcrowded concessions while others are less busy.
There is a strong possibility a lot of people will want to go to the Upper South bar, for the view, but i expect that will be a novelty which will wear off; it won't be a consistent issue. Apparently the South Stand concourses have been designed for a larger capacity than they can currently hold anyway, so there should be plenty of room.
I don't think it can be understated just how much bigger Bramley Moore is to Goodison and how much more space we will have on the concourses, even with the increase in supporter numbers.