Oh, my. I am rethinking getting the camera then. I take pictures of books daily with my T3i right now. Each book is about 1.5-2GB. I will have to buy 4TB HDs every year if I will be using the 1DX for books.
Not getting it? Why? Your photographer has given you pics for use on the web that are 10mb each - seems a bit extreme, given that most pics are displayed on a web site at a size of no more than 1mb, many less than 700k.
I've got a 2tb EHD for backing up RAW files out of the camera and for copies of processed files, and I can assure you that i do not need double that each year, and that was with 5D2's, which produce larger sized images than the 1DX.
By all means get yourself a couple of 4tB EHD's for providing secure back up of your images, but if you are doing that on an annual basis - i suspect you're not charging enough for the work generated by all this activity or you are not processing your files correctly.
Enjoy the 1DX, if i could justify the purchase cost, i would have one yesterday - it is a beautiful camera and IMHO far superior to any thing Nikon has to offer