What happened to Houston?

It wasn't that long ago that the Southwest was coming up due to it's independent grind and the long work put in by artists like Scarface and UGK. Fueled by the explosion in Lousiana rap, the progression to the area just South of Cali seemed to complete the full hip-hop coverage of the map. All at once, Paul Wall, Mike Jones, Lil' Flip, Chamillionaire and Slim Thug threatened to take over the game