I think it just might be a long term shift. I admit to being a JFK Dem in the 60's, and I held onto that (Nixon was scum, and not a reason to switch). I was a Reagan Dem after '80, and didn't switch because clintoon is scum - I thought that was an aberration. I switched to GOP when W was nominated. His political ideas are very similar to both JFK's and Reagan's, and he's an honest and moral guy. And the clintoons still had control of the Dems.
Who's the opposition leader? clintoon? hillary? gore? or gary hart, whose name has come up often lately?
On the other hand, the GOP has waiting in the wings Jeb, Condi, Powell, and a long list of pols with the same ideas and high moral standards.
The Dems have a long way to climb out of the muck, and not a clear leader to help them do it. They either need that, or a real scoundrel at the head of the GOP, and it doesn't look like they'll get that.
A landslide is possible, but the Democrats must cooperate. They appear to be doing just that, pushing one of their flaming extreme feminazi-liberals, Pelosi, to a top leadership position.
I doubt you will see that type of dominance, but if the GOP can keep control of the House it can effectively whittle away at the Democrat coalitions which depend on getting 'paid' by the Party for their votes.