While the “need” for Atmos tools for Nuendo currently is rather low, I wouldn’t be too discouraged.
Console manufacturer Harrison already know exactly how to interact with the RMU without using the Dolby panner. And Harrison is a strategic partner to Steinberg and Yamaha. So while we may not get a Dolby panner I do expect that we eventually get the tools needed to do immersive panning natively and also how to control the RMU.
Also I bet that the first Nuendo mixing facility asking for a VST Dolby Atmos panner (or they will not build a Atmos mix stage) may change this. I mean, if one looks at the panner plugin, it does not look like it would be rocket science.
The only thing possibly limiting this is if the Dolby Avid deal means it is exclusive so no other “new” users are allowed to access the technology. Only the future will tell.