MLS actually does a pretty good job of getting people to games in the home markets. TV coverage does leave something to desire, but I think they renegotiate TV rights next year--and given the investment that NBC has shown in the Premier league next year, MLS might be able to hit it big with someone like ABC/ESPN or Fox, if they're looking to compete for those viewers.
I suppose we shall see. I'm of the opinion that in 10 years, soccer could see a huge boom in coverage and popularity. I certainly hope so, but I guess we won't know until it happens.
ESPN and Fox tried to combine powers to take the Premier League from NBC but NBC still outbid the duo. It would not surprise me to see a big jump in coverage for the MLS if ESPN/Fox want any of the ever expanding market.