Don't believe the pundits; incumbents still dominate congressional elections.
As George Washington University political science professor John Sides points out, 2010 was a pretty good year for incumbents after all.
86% of incumbents won their re-election bid. Though the percentage was relatively low compared to previous years, this indicates that there was no massive anti-incumbent movement ready to kick the establishment out of Congress.
The median percent of the vote won by incumbents (65%) was in line with the historical average (68%). Further, the percent of races with no incumbent running in the general election was 10%, a pretty mundane figure. This refutes the notion that lots of incumbents decided not to run or lost their primaries.
Take this into account when you hear about polls in which vast majorities of Americans disapprove of Congress or even indicate their willingness to vote for a challenger. There has always been a very strong correlation between incumbency and re-election.