Airline's Upcharge for Earlier Check Ins

I heard Southwest is moving away from "free for all" seating. I don't fly very often and I've only flown Southwest twice, if that. But I do remember everyone trying to get in to the gate as early as possible to get good seating closer to the cabin. I am not sure why SW is moving away from it but it got me thinking. What If... instead of selling seats by the status (business, leg room, etc...) Airlines upcharge by checking time, the earlier the check in time the better chances for you to snag up a seat right up front, and the closer you get to flight time the less chances you have of getting good seats... and if you don't want to pay at all then you'll be seating in the Free for All Zone, which is now sounding more like a battlefield than an airplane seating layout. A lot of things still need to be considered so what happens if you pay for extra early check in but you did not check in? Do you still get a seat in your area or will you "walk-of-shame" to the back of the plane? What do you think?