Even if all of these new primary/caucus voters are GE voters in the past, the fact that they've become motivated and educated enough to vote in primaries (and, especially, caucuses, where you really have to care a lot about the candidate...) is a good sign for the Democratic Party. The more motivated our base is, the more they will volunteer, give money, be vocal in support of their candidate(s). I think the increased primary turnout is a sign of a more galvanized and motivated base. This is a very good thing. Not just for our presidental ambitions, but for our chances of gaining more seats in the House and Senate, State Legislatures and Governorships, and building an enduring Democratic primacy overall.
Go look at the delegate counter. I'm an Obama supporter, but the polls and the delegate counts are running around even. We're not talking about some lopsided race where there's a clear consensus nominee. We're talking about a very close race.