I'm an unashamed frontline fan of APS-H. But I think my 1D4 may well be my last APS-H body. From a business viewpoint it makes complete sense for Canon to rationalize to FF and APS-C. What Dr Neuro says about the profitable environment Canon has created to push people into new, longer lenses will chime with a lot of photographers. For my particular needs the 300 f/2.8is on APS-H is practical and ideal. But on FF 1DX the need to dig deep for a 400 f/2.8isII will be essential. So I'll be squeezing maximum life out of the 1D4, delaying the 1DX/400 f/2.8isII purchase.
Another reason for holding off on the 1DX/400 f/2.8isII purchase is the potential for a 7DII presenting as a high quality APS-C alternative to the 1D4. Not that superb 1-Series build/ergonomics we know and love, but a substantially viable, inexpensive sports/wildlife/BIF 1D4 replacement. With even more reach.