I'm not convinced that a shambolic no deal Brexit will make the Tories unelectable. The narrative will be that all the chaos is entirely due to EU intransigence (nasty foreigners) and there will be enough people who buy that line; with the help of Murdoch and the BBC, to make it possible for a Tory party taking a neo-Fascist Trumpist line to get elected. Make Britain (England) Great Again. It will likely lead to Scottish independence but that only reinforces the Tory position in rump UK.