Here's how I see Johnson's term in office ending, if Sue Gray's report ends with something like this statement:-
' I find it almost impossible to believe that the Prime Minister was unaware that the May gathering in the back garden at 10 Downing Street was a social, not work, occasion'.
I think even Johnson would then realise he'd received his P45 , and if he didn't he'd soon learn in no uncertain terms from his MPs. Being Johnson and 'frit' personified he'd make a statement outside 10 Downing Street rather than in the Commons, then have to go face to face with the Queen (oh, to be a fly on the wall!)
I still maintain my position that this will happen by 26th i.e. next Wednesday, but the report may not be available by then of course.