If I was a Tory MP I would wait for the police investigation to conclude and the full Gray report is out before making a decision. I'd find it immensely frustrating that the police are drawing this thing out. It's really doing no one any good including the whole country as a whole - how is a limping PM regarded by leaders outside the UK, especially Putin? - except perhaps Boris who wants people to forget parties. We need all the facts.
It's pretty obvious what has happened. Boris has important strengths in communications and viewing a big picture, but he has always been hopeless on detail and discipline, including personal discipline. As Mayor of London he relied heavily on those around him. But those around him now, especially Carrie, have not been good news. When Boris won his 80 odd seat majority against a useless opponent in Corbyn, Carrie and others convinced him that he was invincible and could make his own rules. If you look at a lot of Boris's unforced errors like wallpaper, decorations, cakes, parties, Carrie was behind it. She was the catalyst to getting rid of Cummings who then became a dangerous opponent with knowledge of all the dead bodies. A spouse can be a strength or a weakness to a politician - I'm afraid Carrie (whose care and concern for animals I admire) has been the latter.
If Boris goes, and I think he will once the police have concluded their work, I'd look at an outsider, Tom Tugendhat, to replace him. He is the antithesis of Boris and the two don't get on. As ex military, he's disciplined. He's bright (his father was a judge), takes a keen interest in foreign affairs and seems to have good judgement. He or Sunak for me.