As of September they were still selling tokens at City Hall and the booth at Powell St. but you have to ask for them--they haven't advertised their existence for many years.
I can't recall the details now but when they first started seeking local Muni riders to try out TransLink, I was enthusiastic and looked into it but concluded it would not be in any way a plus for me and I lost my enthusiasm. If things change (such as doing away with FastPass-accepting gates at metro stations), I'll reconsider, of course. I'm too old to do what so many Muni riders do and just jump the little railing and ride for free.