I've got basal joint arthritis (at the base of both thumbs) and arthritis in the first joint of my left index finger. I take Gluecosamine; not sure if it works or not. My hands still hurt, but I suppose it could be worse...
Anyway, what I've done is buy a Taylor T-5. It's an electric/acoustic with strings and action of an electric guitar. If I didn't have this guitar (or some kind of electric), I don't think I'd be playing anymore. Every once in a while I pull out the acoustic (Martin 00028EC), but it's very discouraging. I'm actually thinking of selling it because I just can't seem to play it anymore.
Anyway, my point is that electric strings/action take a lot of stress off your hands and may extend your playing time by several years.