"In four and a half years I would like to be pleasantly surprised that the milestone is coming up, every so often logging into SR if I need it, and otherwise just out there living and not thinking about it too much. I've met people like that and I just find myself wondering how long it'll take till sobriety is more often (not always, of course) a given in my life than an active struggle."
It's difficult for us to know when we reach that indefinable "milestone," and even more difficult to recognize this in others.
In my experience, by the time I've recognized a positive change in my life, it's already been going on for some time.