The Cummings story feels like something it should be impossible for a PM and govt to brazen out, until you remember all the other things the Johnson govt have already brazened out in the past 9 months or so

The key difference, if there does prove to be one, may turn out to be that in all their previous brazening out enterprises the govt relied on Brexit partisanship, whereas this story doesn't strike me as one its easy to brazen out in that fashion.

OTOH, look at Trump or Berlusconi. Govts which are determined to just barrel on regardless can often survive a lot more than people expect, particularly if they have a core electorate that isn't much bothered by anything they do. Whether that's true of Johnson remains to be seen.