I'm not discounting the possibility of a major Democratic realignment, not at all. But I feel compelled to point out that many of the people excited by massive voter shifts are confusing a) serious Bush hatred during a once-in-a-generation financial crisis and b) massive black voting turnout to vote for the first black president, a definitionally unrepeatable happening with c) actual permanent demographic change in the electorate.
This article available online at:
http://www.theatlantic.com/business/archive/2008/11/how-much-have-voters-really-change/4322/