It does matter how many years or hundreds of entries the blog has, if it has ever gotten an adult content warning for any reason at all it will be gone from public view. This is really not a lot of warning for people who have spent years building their blog and an audience.
What's even worse is that anyone who has ever gone to a Blogger blog knows that the adult content warning (which is how they decide which blogs to nuke) has been applied heavily to sites that deal with gay, lesbian, asexual and trans issues.
Hell, sites that have nothing but stories about men using magic spells to turn into women have gotten the label as have sites that feature attractive clothed people with captions reading "I don't like sex!"
It's really going to fuck a lot of people over and its' really a shame.
Fuck you Google.