Update seemed very clear. Main point is don't leave it a year before logging in or your account will be liquefied. Seems a little on the "fast" side to me. Had a feeling it used to be that you had a year before it got locked for security sensibilities then 3 before being liquefied? I might be remembering wrong though? Wist
Telling from reports of people actually affected, it was inconsistent hinting that they performed a manual purge whenever they could remember, which led to a number also being forgotten and left in peace. I don't know if the announcement means they are now installing a program that won't let anyone slip through the net anymore. When I was in hibernation for several years, I just logged into the web account every time I got a reminder email, which was twice a year. Logging into the game itself or having it installed at all was not required to keep the account. I don't know if this is going to change, too.
Hmmm.... one would imagine a login would be enough... but it would be good to have confirmation. I'm trying to remember what I did during my 3 year break...