Upload & Sell: Off
Follow the glass.
Whichever system has the better glass suited to your needs, is where you should be.
Personally, I don't think I'd put myself in two boats, because I like to have a backup of everything, so that would get expensive real quick. But I can see the reasoning that others would do that - each company does excel in different aspects.
But overall, glass is going to outlast any body... any 5+ generations of bodies for me. I have two 200/1.8 lenses - which originally came out in 1989 - is my most used lens. Only recently did Nikon offer anything on par. (yes, I know about the Nikkor f/2 200mm, but it was MF)
New bodies - with different spex come out every 2-3 years, with usually Nikon/Canon leap frogging each other every other generation.
The other question you have to ask yourself - and seek an honest answer from yourself - will it be good enough? Will the 1DX be good enough for what you need? It's just as much a variable as jumping over to Nikon for your particular aspects of shooting.
Sure, it's always cool to get new stuff, and all new Nikon gear would be more fun than just one new body! And if your a hobbiest with lots of money, then no worries. But as a pro, our bottom line is affected by our assets and expenditures.