The last time that I checked, which was 2 years ago, 31% of the pilots at my employer who were between 60 and 65 were on long term medical. That seems to have decreased, but I have not run the numbers.

There are a lot of variables, and YMMV. I believe that the best generic plan for a pilot is to save for retirement and plan to be debt free by 55ish. Those two steps will make a forced medical retirement nearing 60 a problem rather than a disaster.