Sala definitely said there were plans to change the seating on the lower level (though it seems just about like everything is still not finalized).
I think going to individual seats on the upper level is a problem because they did not include room for chair backs in the 300 sections like they did on the lower level. If they include chair backs, I think anyone over 5'10 is going to be miserable. If they want to go to individual seats, they might have to forgo seat backs, or replace the existing concrete sections completely.
I think they want to keep the size of the roof as small as possible to hold down expenses, hence the need to retain the original roof ring.
There might be 30 feet from the exterior walls to the roof ring all around the perimeter of the dome. The load bearing columns will continue to be under the roof ring and the new exterior walls will be held up by less hefty columns along the perimeter?
Weird.