Basically I won't be happy even if it doesn't affect the image much given that it is a expensive camera and non of the cheaper Nikon camera has this major an issue with dust.
I am holding back my purchase until they fix this damn issue.
Technically D600 is a cheap camera. It's the cost of the sensor and design that makes it expensive.
Considering a DX D100 at $3.6K 9 years back, and a FX D600 at $2.9K now, it's not really considered expensive.