Super New

The more mature a technology is, the harder it is to release a really jaw-dropping product:

So even if the engineers manage to improve an already near-perfect model, the new camera will not really be all that different.

That is exactly what happened in case of the Nikon D6: Like the D5, it still is a lighting-fast camera, it still has incredible high ISO performance and it still is indestructible. On top of that, the autofocus was improved significantly, but no one really took note of that, as the D5 was already practically infallible.

It is important to understand that major breakthroughs in physical engineering are far less likely to happen and if they do happen, they often go relatively unnoticed.

Always keep the Pareto-principle in mind: An improvement of 20% requires 80% of total development resources and is neither needed nor noticed by 80% of all users.