Whatever that stuff is, it's not the "kombucha" like we make at home.
There are probably some yogurt products that last for 2 years but yeah what's the health benefit of those? Probably not much. They usually have a ton of sugar and are pasturized, and I'd guess the same about 2 year old Kombucha.
Some brands have started "spinning" their Kombucha basically to draw out the yeast and alcohol. I'm not sure how much health benefit is preserved, but I have found those brands to grow a partial scoby when added to sweet tea. Kind of like fresh vegetables I think the closer you get to the source the more benefits there are.
Jared