I'm afraid I can dismiss everything in your post as wishful thinking. You hope that there hasn't been an ideological shift, despite the evidence of a landslide election and the rearrangement of the electoral map; but the reality is that we'll only know after the fact whether an ideological shift happened. Same dismissal of the highly spun interpretation of history.

Specter was unusually candid in explaining why he switched, and I still haven't made up my mind whether that was refreshingly honest or nauseatingly craven. It raises some fairly deep questions about what we mean by "representation" in a republic. Should a member of Congress (unlike the judicial or executive branches) be a high-fidelity conduit into Washington for his/her constituent's beliefs; or should a representative try to lead the constituency to accept his/her beliefs instead? Judges definitely no; Presidents some of the time; and I'm leaning toward the view that Specter did exactly the right thing in changing his party affiliation to match the changing affiliation of his constituents. He's a representative, not an executive or a judge; what else could the job title mean?

At the end of the day, it's the voters in Pennsylvania who'll judge Specter. They've been electing him for three decades, and I suspect they'll reward him this time for his reciprocal loyalty in following them to the Democrats. You'd be overlooking the most crucial factor of all if you overlook their longterm relationship.