Does Nuendo support native DSD recording?
Short answer : No.
Long answer : There is a market for this, but DSD primary interest is acoustical sessions two tracks recordings, without processing and limited editing (crossfades, cut and paste…).
As soon as you want to mix or process DSD tracks, you need to convert them to a PCM or hybrid format, then you loose the specificities of DSD one bit recording and playing.
Then DSD is more an audiophile format, and will perhaps, or probably survive because it is very different compared to PCM.
My opinion is that DSD is not useful for multitrack sessions. Mathematically it is a hassle to convert, process and analyze, and cause some problems for levels and DC offsets because of the 1 bit nature. Levels problems is not something we can tolerate in a professional audio workflow.
More, PCM 96 KHz, 192 KHz and 384 KHz 24 or 32 bits audio interfaces are very common today and reduce even more the usefulness of DSD.
Last, Yamaha is not involved in the DSD format and hardware. So there are very few chances to see that inside Nuendo. It is more something that could be implemented inside Wavelab with more usefulness.