Right, though, if we reach that extreme design (i.e. round sensors) I bet mounts design would have changed before that (and many other things around us probably ). Even cross-shaped FF sensors would need some room at the bottom where the contacts are nowadays. The moving/rotating cage would be another way around to keep the actual mount design.Un
Unfortunately the R mount contact base would obscure a square or round full frame sensor but for aps-c it would work .