Absolutely no compelling, or even particularly good, reason to. But I do have several good reasons to stay.
I do use the RT flash system a lot, though that could be done with Nikon via the Phottix Odins, I use the 17TS-E a lot and that can't be copied by any other system. I have a $20,000 investment in Canon that owes me nothing and I, and the clients that paid for it, are more than happy with the output from my 7 year old cameras.
If I were to switch to new gear it could only be Nikon, it would still be a DSLR, I would have no size or weight advantages and several lens disadvantages. I would have slightly better IQ in some situations but they are not my normal shooting scenarios, if I sold my current gear and bought closest equivalent new Nikon stuff it would cost me another $10,000, if I bought used it wouldn't cost me much but I'd lose my most used lens.
I am happy with what I have, I would like a 1Dx MkII to have 24MP and then I'd replace my 1Ds MkIII's and I am pretty much set for the rest of my working career, sure there will be ever more improvements, and I'd like them, but I won't pay for them because to me this gear is nothing but tools and anything I spend on them is money I can't spend on me.