I don't know if I buy that. I think that was reported by a tabloid. I am a HUGE Stones fan and if this is true and if it helps him play better, good for him. The past few tours you can really notice a difference in his playing and missing notes, etc.
Of course, some of that could be his arthritis.
Yeah it was just rumors. Keith Richards told that to Rolling Stone magazine recently. Maybe it was just a passing statement about wanting to quit and someone quoted Keith Richards as saying he was going sober.