Looks like it will be steel frame, not to mention higher labor and land costs in Cali.$937 million??? That's far more than the estimated cost for the London Olympic Stadium, if you convert US Dollars to British Pounds.
EDIT: and almost as much as the New Dallas Cowboys Stadium, while the new 49ers stadium is much more basic in its design...
the gap is there for the same reason they are in Cleveland Browns stadium; to steer notorious winds that get trapped in bowled stadiums in that area. Read this on the 49ers forum, that wherever their stadium ended up they didn't want it to have the swirling wind that Monster Park has.Please fill in that corner in the 2nd tier!