I'd say so.
Michael Gove has apparently declared he's staying but has privately told Johnson to just go.
If thats true, it doesn't really sound like he has the continuing support of those MPs who say they are staying.
And that makes me think, that their position may yet change if Johnson doesn't go (and the only reason they are currently staying is for their own reasons or to try and save Johnson the embarassment of them going too).
I would watch carefully, because the bigger the number going, the hard it is for Johnson to replace government roles with backbenchers (who seem to dislike him even more) and the more untenible the position for those who do remain in Cabinet.
Also watch for the sharks circling for position in the Next Great Tory Leadership Election. (I do like a good Tory Leadership Election. Its better than a soap opera).