Democrats are going to have the Millennial politicians who learned their political techniques from Barack Obama. That's a very good model.
Millennial adults will likely vote for Millennial politicians at the expense of Tea Party types. Such will be big trouble for the GOP.
The problem is the Democrats seem like a party of geriatrics - Bernie Sanders, Hillary Clinton, Joe Biden, Jim Webb, Nancy Pelosi, Harry Reid, Dick Durbin, Chuck Schumer, Steny Hoyer, etc. etc. etc. Not a single real leader under 50, not many under 60 either. They do a terrible, terrible job at supporting young talent.