I've had this in the back of my mind for awhile now, and I've changed my opinion a little. I wouldn't mind Subban getting in a game or two during the season like Svedberg did last year, but as a serious backup, I have some doubts. He's a little too young, and something would really have to blow up in Svedberg's face to cause a switch, since Svedberg has a one-way contract. I think keeping him boiling in the AHL pot until he's at least al dente might be a good thing - a raw goalie that doesn't stick to the wall is a bad thing.
An intriguing option would be Brodeur. I've been waiting and waiting for him to be picked up, and the crickets are still chirping. It's clearly an issue of a goalie surplus - my gut tells me he would have been a reasonable addition to a lot of teams, including even the Bruins. If we have a serious goalie injury (please Jeebus no), the Rask/Brodeur or Brodeur/Svedberg combo might be reasonable - both combos allowing Subban to simmer in the AHL.
I have no idea cap-wise if/how this would work, and I have no idea what kind of salary Brodeur would command. Would it be so high that a Svedberg injury wouldn't leave enough cap space, and thus he'd probably only replace Rask?
According to an article I read today, Marty is willing to sign even after the season starts, and would ideally like about 20-30 games - which is basically a pretty standard backup goalie load, perhaps on the heavy side (especially if those games are concentrated later in the season). Last year, HICJ played 27 games, with 1 for Svedberg, and I think Rask might be willing to accept a similar split, even though there's no issues this year like Tuukka's Olympic run.