I would go one step more.
I doubt if John Kennedy could win the Democratic nomination for president in today's Democratic Party.
Considered very liberal in his day, but now ?? Perhaps moderate ??!!
Great analysis!
The recent democrat presidents you mentioned also all had oafish, embarrassing brothers. JFK had Teddy, LBJ had Sam, Jimmy Carter had Billy, and Bill Clinton had Roger. I've always wondered if that was a coincidence, or an indication of something more.