What's the fix you mention may I ask?The crank bearing problem is the plastic race used to separate the ball bearings. When this race goes bad, it is pretty apparent. If you are not handy it is a PITA, but if you have the time and some tools it can be fixed rather easily and cheaply.
Personally I think the plastic cage may be a red herring. The cage isn't load bearing, it just holds the needles in position and separate. Big name bearings of this type like SKF use plastic cages. As a matter of fact the bearing on that MS261 that I inspected was perfect, but there was still significant play. I had a spare new bearing and that made no difference.
According to Stihl UK the problem is the clutch drum being out of round. I assume that knocks out the bearings, and in turn that wears the crank. Or it wears the bore of the drum oversize and that causes the crank damage. Or it maybe that the cranks on some were weak in some way and too easily damaged. Reports are mixed. Stihl's answer would explain the rather strange suggestion that switching to spur sprocket fixes it. Stihl gave a part number for a modified drum (1141 007 1002) and reckon that fitting this to a so far undamaged crank would be a solution. But on the other hand they claim only very few saws were affected, which doesn't tie up with end user reports.