As a 1DSIII owner and landscape photographer I am still looking for Canon to give us at least the equivelent of the Lieca S2 as the replacement for the 1DSIII! The 1D X will be a great camera for the PJs and probably the wedding photographers also. If i was starting from scratch, with no cameras at all I would probably buy the 1D X although it is not really the camera I would prefer. (Hassys cost too much) Canon has the technology to give us 50/60 MP at 16 bit @ 1 FPS which is what the landscape shooter wants and needs, and I beleive that the EOS mount will at least support the S2 format and still allow us the use of existing lenses. Canon knows about the PJ market but I don't think they realize how many landscapers would jump on a 10K MF camera. Pentax is an Iffy company, and Minolta has disappeared from the MF scene.
EOS/EF lenses would work on a sensor the size of the S2?
My guess would be the part of the reason for the 1Ds being phased out would be that with the 645D around they want to maxmise the size/cost advanatges of a FF high megapixel camera.