Although to an extent, Johnson is ‘priced in,’ it’s still noticeable how little people have seen of him. Between him, his team and the press, the public have a very filtered view of Johnson’s public appearances and his attitude to any scrutiny.
While I don’t expect that to change a great deal, I do think that there is still a significant prospect of him letting the mask slip with a member of the public, and if that happens with a brexiteer, it could go wrong for him.