someone mentioned that Canon could do something bold and tool up with the largest possible APS-C sensor that would accept an APS-C lens, in order to squeeze every possible bit of IQ. Sort of a "get as close to H" as possible.
While the motivation for this is admirable, and conceivably there may very well be some largish C sensor size that would still provide all the various geometries in the mirror box required to accept the C lens mount. I rather suspect, however, that Canon has boxed themselves out of such a possibility due to the existing (and expanding) APS-C lenses which, by virtue of their 1.6x design point, do not have sufficient image circle IQ to support anything larger. for example, as cool as it would be to have the 10-22 suddenly turn into a 14-32 FF equivalent instead of the present 16-35, I wonder what the edges would look like...