if henry comes to america it will furthur increase the popularity of soccer in the US and thus it will help everything about soccer in america in the future
I agree with another poster... Bringing big names to MLS, even if they are past their prime, only increases the relevance of the league and the notion that this is and always will be a low-tier league. MLS will never be on the level of the English, Spanish, or Italian leagues, but it can be relevant on a global stage.
If Henry comes to the U.S. in the next few years, I'd expect to see him in New York or Los Angeles. More likely New York.
I'm sure Henry will eventually make his way over here sometime in his future. I have also heard through rumours that L.A was going to make a huge bid for Ronaldinho to come over but that's probably false anyway. It will probably end up the same way when Figo was rumoured to be coming to L.A but that never happened. I think many of these superstar players will play out most of their career in Europe and finish their careers in the MLS because the American teams will pay these old superstars the money that European teams probably won't offer them anymore due to age.