My comment above was indeed my first announcement of returning to Nikon, and FX.
An FX camera with the 16MP sensor would make more sense in this context, but neither Df or D4s was within my budget.
Welcome back to Nikon Akira and thank you for sharing the reasons behind the switch, its always interesting what drives others in their choice of gear.
Myself I'm also on the fence to add the Nikon D500 to my arsenal, there's only one thing standing in the way besides availability and thats my desire to own the Canon 100-400 and those two don't mix

One of my reasons to switch to Sony is the ability to cherry pick lenses from multiple brands but a camera like the D500 is the reason why I fell in love with Nikon as a brand (top performance in a tough and dependable package).