"and have managed to bump off a good number of their voter"
Not even necessary.
According to a Guardian piece by the head of YouGov given UK death rates and the profile of the Leave vote that majority had died off by about Jan 2019.
History will probably record Brexit as a "perfect storm," where a cretinously weak PM, in a desperate attempt to keep his party together and in power (and for no other reason) allowed a gang of delusional Aholes and pocket-lining thieves a chance to use stolen personal data to pitch a total fantasy to a large group of desperate, unhappy and gullible people.
Meanwhile sensible people thought the benefits of membership so self evident (Maybe they remembered what state the UK economy was really in before the UK joined in 1975. Maybe they had the critical thinking skills to spot the insane bu***hit the Leave campaign were spouting)
they did not take the threat seriously, leaving Leave to peddle any lies they wanted through the Facebook
lies, conspiracy theories, hate speech, mad ravings "news" feed.