

Dpreview published an interesting article breaking down the cost of switching from Canon to Sony. In most cases, Nikon's pricing is very similar and the same article can easily be applied to switching from Nikon to Sony:

Using our example, the cheapest one could go full-on Sony, with most of the same kit is $22,870. After applying the $11,820 discount from having sold off all the Canon equipment, a photojournalist would still have to cough up about $11,050 to make the switch. Or they could simply take that $11,820 and buy a couple of a9 bodies and maybe a lens.

I would not recommend anyone doing any switching before we see how the $4,500 Sony a9 performs in the field and before we see what Nikon's mirrorless solution will be (there will be one).