I did upgrade my D700 and purchased a D3s prior to the announcement of the D4 and D800. I do not regret this move mainly because having the D800 at 39MP is way to big for my type of photography, strictly for pleasure. I also do not have the proper hardware for that much MP and will not print more than 13x20. If the D800 was made available at 16MP maybe I would have considered it. As far as Video - I am not using it - strictly still photography.
I like the D4, of course, mainly for the wireless communication system - but 6K is too expensive. I rather invest in a new lens.
This is my opinion for now - will see what the future will bring. Jacques G