Chicago Tribune Chicago, Illinois Sunday, March 05, 1978 - Page 165
Fischer vs Machine
Chess — A reader writes: “I don't hold to the theory that a great master must play regular tournament chess to keep in practice. For example, Emanuel Lasker had not played for 9 years when he was 66 and had to face Euwe (a year away from the world title) in the first round at Zurich 1934. Play the game over—it is a masterpiece. If there is any parallel between Fischer and Lasker (and there is) then it won't be necessary to offer alibis for Bobby. He can beat Karpov or anyone else.”
I also believe that Fischer's rust would wear off very quickly if he returned to the arena.
Although Bobby refuses to take on human opponents, apparently he is willing to play against machines. Recently he slaughtered the Greenblatt computer program in 3 games which he submitted for publication to the Computer Chess Newsletter. It is hard to judge strength against such weak opposition, but they shed the only light on how good Bobby is today.