Majority of US voters becoming more "European" in their outlook?

This from Crooked Timber seems hopelessly optimistic to me, but on the other hand does sounds nice:

"On the one hand, the Pew Survey shows that Democrats and Independents are becoming pretty similar in the views to people elsewhere in the developed world (such as Europeans) – liberal on social issues, moderately social-democratic in social policy, preferring peace to war and so on. Not surprisingly, this translates to a strongly negative view of the Republican party, just as it does everywhere else in the world.

On the other hand, Republican support is contracting to a base of about 25 per cent of the population whose views are getting more extreme, not merely because moderate conservatives are peeling off to become Independents, but also because of the party’s success in constructing a parallel universe of news sources, thinktanks, blogs, pseudo-scientists and so on, which has led to the core becoming more tightly committed to an extremist ideology."

And what's happening to the Republicans' core vote? From this graph they've got some hard work to do: