I have just been reading how the chattering classes expect Johnson to behave as PM. They offer "three versions of Nixon".
Version 1. Nixon goes to China.
When Nixon went to China in 1972 and a thaw in Chinese/USA relationships was observed, it was put about that only Nixon, as a fervent anti-communist, could achieve this. In the same way, Johnson's supporters are suggesting only he, as a lead in the Leave campaign, has the credibility to compromise the hardliner, no-deal Brexit position.
Version 2. Madman Theory
This was Nixon's supposed strategy re the Cold War. If he was seen as so unpredictable he might actually move to nuclear war, other leaders fearing the uncertainty would comply with his demands. Where Johnson is concerned he needs to seem so indifferent to the damage no deal would do that the EU would change or even remove the backstop.
Version 3. Scandal, failure and premature departure
I imagine you can work this out for yourselves. Either of the first two versions of Johnson could lead to this as could any idea of prorogation. I imagine even his greatest fans could see this as a possibility. Prorogation, on its own, could do more damage to the Tory brand than Black Wednesday did to its hard-won reputation (already in tatters with many once again) for economic competence.
This is my reading of the piece which is today's Brexit Blog chrisgreybrexitblog.blogspot.com/. It tells much more of the reasons these theories could rebound on the arch Brexiteers.