I suspect it's already leading to an increase in expressed racism and bigotry
That's what seems to have happened in the US since Trump became Potus. Like Mr Johnson, Mr T has a track record of saying things that many find offensive but he gets away with it. His base supporters love the way they now feel free to "say stuff we haven't been allowed to say because of PC gone mad". Same with Mr Johnson, we can make homophobic or racist comments, its fine. We now also have a glorious leader who does this, therefore "the PC gone mad lot" can just off.