ya, i'm not sure how much of the mall is directly under the plaza. i think a lot of it is under stelco, thomson, etc. might be wrong, though.
i like the skylight idea. i would also close the plaza completely. it serves no purpose other than as a smoking area, as was already pointed out.
here's an image i should have included earlier:
my dream of razing the mall and recreating the former street pattern, rebuilding the market, etc., is just that, a dream. redesigning the king-james entrance and having more access to stores from the street would help. a little more realistic anyway.