That's Houston's problem, if the Sounders played on Sunday they would have a full house.
Well, the Seahawks and Sounders share a stadium so they can't have a match when the Hawks are in town, that makes it more realistic to sell out when the "competition" is multiple states away. Not to mention that the Sounders have an extremely dedicated fan base, regardless of the NFL. At least the Texans are awful this season and play their home game at night this week, not midday. Dynamo attendance should be decent this weekend.