Like others have said, they CANNOT close in the south endzone corners. Get it through your heads. The slope of the sidelines is steeper so you wouldn't be able to match them up.
As for the north, I'm not sure if that is more feasible since I know the slope of the north endzone is actually steeper. Whether it matches the sideline I don't know.
I agree with the scoreboard updates, and MAYBE looking into luxury boxes on the east sides, though I'm almost sure that also isn't possible with the road there.