Re: cocoons and cell size
The first job I had as a youngster, we had some combs that were 40 years old and more, which could be verified because there had been a design change in the frame at that time.
The foundation used was 5.5 mm. The cell width was very little / no different to brood comb that had only seen a few cycles. We believed the bees must clean down the cell walls regularly. What did happen though, was build up on the bottom of the cell. This may have been encouraged because we used 35 mm end bars, and only ran 9 frames to a brood box. In fact, the frames over the years got a build up of propolis that eventually went very hard on the end bars and the frames were not closed all the way up, so the gap between centres was wider than natural.
This meant that cocoon build up on the cell bottoms could go quite thick, with no effect on the bees as they had room to extend the cells outwards. However we did get combs where buildup was so thick that the bees could no longer rear brood in that section and there would be a bald patch in the comb. At that stage we removed and replaced the comb. However this did not happen as much as, in theory, you would think it should. We would also sometimes see old, heavy brood comb, which the bees stripped right back to the foundation, and were in the process of cleaning before rebuilding and we could find the cell bottom cocoon buildup bits on the hive bottom board and out the front, so it does happen. So to me, I think the bees must have some mechanism to reduce the cell bottom, although some bees clearly could not as we had to replace combs, this probably varied from hive to hive. In any case, cell size (width) does not reduce to any significant extent regardless of how many generations have been raised in it, but bottom buildup may occur.
So, a feral hive in pre varroa times, should not, in theory, have had too much difficulty with the "mechanics", of surviving for up to around 40 years. After that, it would have depended wether they were a bee that stripped and cleaned cell bottoms, or not. It could be, that in a reasonable sized cavity, if a section of brood comb became unusable to the bees, they would abandon it and raise brood in another area. The wax moths would destroy comb in the abandoned area and faciltate possible re-use of that area at some future time.
All this just my opinion, take it or leave it, the musings of an old beek.
"Thinking Inside The Box"