Animalsbarry sent me this:
“Talked to Sigma tech rep: Sigma will not be making a NIKON version of the mc-11 ever. The reason for this is that there are differrences in how the Nikon lenses work that would be problematic, so Sigma decided to only make Sigma and Canon versions because they are easier.”
Sigma’s new MC-11 adapter cost $249 and will ship in April according to BHphoto (preorder here).