Will The Dems and the Left Return To Moderation And Sanity?

I think about this all the time. Is there any possibility of the Democratic party returning to the relative sanity of, say, the Clinton administration? Or even the 2008 version of itself that elected Obama? 

I used to think the answer was yes. 

I now doubt it. 

I still think it can revert back in the direction of the mean.

But I now doubt that they will ever completely shake the illiberalism that has so possessed the party.

We used to have an advantage over much of Europe--or so I thought--in that we didn't have a permanent, extremist, leftist faction. 

I'm inclined to believe that we have one now.

I fervently hope I'm wrong.