As announced previously, I don't make predictions anymore. I've certainly heard a lot, though.
Most are based on polling. I live in a "contested" Congressional district, and I've been called at least a dozen times by alleged "pollsters" over the past month. Most, of course, were trying variations on "push polling," using questions in attempts to influence my positive and negative attitudes towards the candidates, but a few seemed unbiased and legitimate. Since I'm retired and have a lot of free time, I participated, mercilessly teasing the push pollsters, and sharing my opinions with the legitimate ones.
Yes, we geezers are far more likely to participate in polling. Part of it is that pollsters, unlike many others, are still willing to listen to what we have to say. Also, every one of the calls I received came on my land line — and a substantial majority of the young people I know don't even have land lines (unless they've been forced to move back in with their parents), and only can be counted on to answer their phones one time out of five. Are they being polled by IM? I don't think so.
Parents with young children in the house don't have time for pollsters. People engaged by favorite television shows or sporting events can't be bothered. Those most likely to respond among those of working age are the unemployed and the ax grinders. I honestly can't see how telephone pollsters can possibly assemble an unbiased sample these days.
I also suspect a sort of Heisenbergian effect of polling in that the act of trying to measure public opinion changes it. Are Democrats going to be dismayed and discouraged from voting by poll results showing Republican strength, or so terrified by the thought of Tea Party victories that they will be certain to get to the polls? I don't think anybody can say for sure.
One thing is certain, though. If the punditry is correct, and Republicans score massive victories on Tuesday, we'd all better hope the GOP has been lying about what it intends to do if it comes to power. Spending cuts never have reduced unemployment, and tax cuts never have reduced a deficit.