True but that partly depends on whether people are taking this into account when they respond to generic ballot polls. So a comparison of generic ballot polls from the same pollster in 2002 to 2010 may be a better comparison than a comparison of generic ballot polls from 2010 to the 2002 actual results. Even this is vulnerable to methodology changes, but it is at least as good as comparing poll aggregates across years, because the makeup of these aggregates may change.
In
Gallup, the GOP generic lead starting with a breakout in late July in 2002 was 6,8,3,5,5,9, and 5, average 5.9%. Here we have the same breakout in late July and leads of 5,6,7, and 3, average 5.25%. I suppose taking into account polling effects makes the picture look slightly better for Democrats, but not in a really significant way. As of now, Boehner is still probably going to be the next Speaker.