It will never pass the city population. But the metro populations are definitely in play. It's very likley LA will pass the NYC metro, wether it's in our lifetimes or not, barring some massive earthquake.
However, I don't think much would change because its so isolated. NYC is in a perfect location to maintain it's dominance in many areas. But it's going to be interesting to see LA grow up though.
It's astonishing a place like this got built, when you fly out west over hundreds of miles of NOTHING to get there.