"Hmmmm, when I had my 100's, I thought John said that they wouldn't take any of the X000-series drivers due to size incompatibilities...."
Most likely he had not adapted the new drivers to that particular cabinet yet. Over time, he seems to work out how to adapt the newer drivers to as many old cabinets as possible, thereby providing the most potential upgrade paths possible. I do not think he would advertise or sell a new driver on an old cabinet until the combo can be tuned properly. Just plopping a new driver on an old cabinet would not be an optimized solution in that each cabinet's acoustics are different. Eventually, these get published to the web site at which point I suppose they become a formal product upgrade option.
A significant part of OHMs business is providing upgrades to older units, which both helps keep costs to current owners low and helps keep the customer base intact. If teh upgrade is not published on the web site, then its availability would not be assured.
