Is the prominence of foreign drivers in the league hurting the IRL?
Well, I don't believe it is hurting the IRL anymore, however, it definately isn't helping the situation either. I know what hurt was when it actually happened and US Drivers were being left out of the series for Euro and South American drivers. Obviously, that is when most of the fans left the IRL that wanted to see US Drivers running, but now that it's been this way for a few years, I don't believe it's hurting at the moment. I do believe more American drivers would help the series, but right now, we aren't being hurt by the lack of American drivers.
I don't even think it is American drivers we need, but we need names that sound good for Americans. I think it is all about how the name sounds to the audience. I think having drivers like Vitor Meira, E.J. Viso, Hideki Mutoh and Bruno Junqueira are the ones that have trouble gaining fans, and attracting fans to the league. North Americans (and more specifically, Americans) find things they are used to friendly to them. I think names like Scott Dixon, Justin Wilson, Will Power, and Ryan Briscoe can blend into the American audience's minds much easier then european names. What I am trying to say is, when you hear the name Scott Dixon or Justin Wilson, you don't automatcally think of foreigner, whereas names like Helio Castroneves and Hideki Mutoh remind the audience of foreign drivers.
I think more US drivers will help the series, but I think running foreign drivers with more American sounding names can trick the audience for a while, not nessicarily forever, but for a while, maybe long enough to get that audience to think of them as their favorite drivers.