Sadly, any of those RATs might win in a presidential year. You forgot about Meehan, Tierney and Robert Reich. And you didn’t mention Lynch or Neal, perhaps because they are (at least nominally) pro-life and would have a hard time winning the Dem nomination. But any of those Democrats have sufficiently high name ID that they will be tough to beat in a presidential-election year. Brown was able to ride a perfect storm to win by 3% in a low-turnout special election, but he will face a much tougher environment in 2012. Whoever wins the Democrat nomination will start off as the favorite.
I did forget about Tierney, a definite B-lister, and Meehan, who’s been out of politics, but I suppose he could come back in. Robert Reich is at UC-Berkeley. Not that he ever crossed my mind anyway. Wierd thing: I see Reich is from the same home town as Joe Biden and Hillary Clinton: Scranton, PA.