It'll all boil down to cost and convenience. Most Americans I suspect would rather drive or fly than take a train, even a high speed version. Gas is still relatively inexpensive and airfares are still pretty decent.
In Countries with high speed rail, gas is taxed at the pump and passenger rail is in turn subsidized not only for initial construction but also ongoing operation. Elsewhere in the world, high speed rail lines often barely break even or are money losers.
http://www.washingtonpost.com/wp-dyn...021605977.html
Given the US's geography, preponderance of wide open spaces and limited areas of population density, high speed rail lines would have limited application in this country anyway.