To be frank, I feel that the US is just not capable to producing F1cars and drivers. <EDITED WB>
Are they? I thought they usually missed their targets.

Ever heard of Mario Andretti?
Getting back on topic....
The US already has high profile series in NASCAR and various Indycar series. F1 is not high profile enough in so much that there is not a US GP (yet). NASCAR and Indycar is more of an attraction as they offer pretty much the same to drivers as F1. It's a bit like a British driver choosing to go into NASCAR or Indycar and not F1. Not exactly a common occurance without going through F1 first. In fact Dario Franchitti is the only UK driver I can think of that went straight to Indycar without going through F1.