Johnson will cling on, because vanity. He knows he has been rumbled, he has known for months but carried on lying and eventually the lies catch up with you. He has humiliated his party and his cabinet, yet they were still prepared to go and soil themselves on the media this morning on his behalf. I wrote a post earlier today describing the Johnson adorers as a cult, that is evident from the twitter trolls and bots proclaiming their love for him to them denying reality with their ludicrous scum media claims.
To paraphrase James OB "i have condemnation for the conman, compassion for the conned" and the lying narcissist has show he is not the great showman, he is the great conman.