Where are they becoming more extreme? 

And even if so, don't you agree that EVERYONE is more extreme?  

Looks at the political viewpoint charts.  Over the past 30 years the right has moved way right, while the left has almost remained the same.  Political correctness is no worse/different now than 20 years ago.  That landscape isn't changing, it's just that the right is pushing back more now and it's encouraging their folks to keep pushing.  But in reality, nothing has changed.