How far are we from developing a technique to regenerate cartilage in ra patients by stem cells or some other method, one decade or more ?

Probably: Stem cell therapy shows great promise in treating a wide variety of diseases including ra. Clinical studies are underway (mostly outside the us- regulations regarding blood product harvest and use are arduous in the states) and should they prove safe and effective over time they may prove a viable treatment option. I think your estimate of one to several decades before widespread use is likely.

It's Possible: Check out Regenexx.Com. The have the single largest registry in the country of patients with degenerative joint disease that have used their stem cell procedures with good outcomes. Obviously not everyone gets better, but a majority have found some success even in patients with RA.