Politico's Dan Hirschhorn has a nice story today on the expected post-redistricting matchup between Jason Altmire and Mark Critz. He gets confirmation from the Critz camp that the Johnstown Dem will run for reelection next year, no matter whom it's against, and notes that both conservative Dems will be put in the uncomfortable position of having to run to the left to win the 2012 primary. (How conservative? Altmire joined with an ultra-right Republican to introduce gun rights legislation yesterday, and Critz was rated as even more conservative than Altmire in the last National Journal rankings. Though by just a tad.)
The latter point is especially significant since both men faced tough races against Republicans last year (Keith Rothfus for Altmire, Tim Burns against Critz) and will certainly face a strong GOP push next year too. They can only hope Republicans have a competitive primary too.
Here's a possible look at redistricted Pa with Altmire's PA-4 dipping into the old PA-12 to pick up Critz's home in Johnstown, by Cook Political Report's David Wasserman: