Most people are pretty happy with their own representative, even those that are unhappy with Congress overall. After all, they get elected every two years, so they have to keep their voters happy. Senators are a somewhat different issue, as they hold office for so long that there is a good chance of "buyer's remorse" setting in, or short term animosity going away before the next election.
This is by design - the House was intended to be as close to an up-to-the-minute barometer of public will as was feasible in the 18th century, while the Senate was always intended to look at the long view instead of what often turn into brief trends. This is also part of why the position of Senator was originally an appointed one instead of elected - theoretically the governors would pick wise statesmen that could get along. That part didn't work out so well, and it was changed.
Barring something very unlikely -such as a sneaky nuclear strike or some Japanese airline pilot deciding he's mad at the US- the retention rate of Congress will probably stay within the range it has always stayed in.
(Incidentally, does anybody know if statistics on congresscritter retention rate have been analyzed by anybody?)