And Mexico is eying for a race. So, goodbye to Mexican fans.
Mexico is still years away from a GP, unless a guy like Slim gets involved. Besides, it's not really a problem. I don't think Southwest/Southern USA will have a problem attracting people to an F1 race. It's got a huge, growing population.
I definitely think North America can have 4 GPs/year. After all, it's a 400+m people, and forecasted to grow further this century (USA will be 400m by 2050, Mexico will continue to grow and develop). I think we've reached (or we are about to reach) a point an equilibrium point of 20 GPs/season, with around half of them in Europe and the other half outside, split between Asia and North America. You just can't pass up North America's marketing potential but you also can't pass up South America and Asia's growth.
Ecclestone plays it smartly, gives USA a second GP and prepares for a bidding war once Mexico's got a firm GP proposal in place. Anyway... we will see what the future holds, but, as I said, I don't think you have will trouble filling up stands in Austin. It's a fast growing city with Fortune 500/1000 companies and a hot bed for IT ($$). Indianapolis is in the middle of nowhere and had no trouble attracting 200,000 spectators. It will be the same for Austin.