the big shortcoming of 35mm systems of course are the lenses, not the sensors.
not much changed here just because the digital part of both worlds became better and has more pixels.
my assumption that the upcoming 17 and 24mm tse lenses of canon will be better in terms of edge sharpness and especially of distortion still has to be prooved, after these lenses will be available. if they will be better ( because for me the current canon 24tse , or schneider 28pc, or the older 28/35m nikon shift lenses are simply out of discussion for their bottle glass qualities ),- 35mm will be a serious option, if not,- the things will remain the same than now.
its a lot of hassle and much more time consumptive to eliminate this 35mm -lens issues than to start with good corrected files coming from medium format lenses using schneider or rodenstock glass, independent of the final digital output.
if someone works a lot its the cheaper way to work with mf because its faster to deliver professional quality,- although the initial investment is much higher. i dont speak here about the lower level work or work which affords to shoot hi quantities of images and where the clients want an acceptable but not outstanding quality.
the new 5dmk2 delivers very good file quality, so i am back to use 35mm too, but for the longer focals above 100mm and for aereal shootings.
for the wideangle shift work my artec together with the rodenstocks hardly can be beaten in terms of quality and efficiency.
but as i said above, resolution is the last important factor here.
to come back to the topic: therefor it dont make much ( if any ) sense to try out a p65 with a retrofocal camera/lens system for architecture shooting.