Rumors of an Anchorman 2 all seem to have started back in 2012 when Will Ferrell showed up as Ron Burgundy (the character he plays in the movie "Anchorman") on Conan
Since then he has shown up countless other times in character as Ron Burgundy (Again, if you don't know, Ron Burgundy is the character he plays in the movie "Anchorman").
He has been in a ton of Dodge commercials
He even showed up to do an actual newscast in North Dakota one night
He was also on ESPN as Ron Burgundy (FYI - Ron Burgundy is the character he plays in "Anchorman")