This probably came to mind because of all the discussion going on about "something new."
Once again, it's TV shows that come to mind. I remember when detective/cop shows were mostly single protagonist like Columbo, Mannix, Kojak, The Rockford Files (or partnerships like Cagney and Lacy). Then, with things like Hill Street Blues and NYPD Blue the shows started to take on more of an ensemble approach, and a big compliment at the time was that they were, 'like novels.'
I guess things like The Wire took it even further.
Today, in novels, though, it seems like the single protagonist is still the most popular. Is it? What do you like?