That's a very good question. I read some time ago that AMD was suppose to implement the SAM function to most of their models. I don't know if this will be entirely true.
There are Bios files available for MSI and Asrock x399 motherboards,. If their customers could already benefit of SAM feature, than I would expect that Asus can't be worse.
According to this redditor , ASUS has no plans to implement support... if true I'm done with ASUS. I'm eagerly awaiting the new Threadrippers and currently looking at MSI for that build.
I guess asus feels those of us who adopted this higher end platform from them don't feel we deserve any long term an loyalty support. Guess asus doesnt care, at least an official statement would be nice from them. Asrock an msi have gotten my interest now that they've proven they offer long term support on their enthusiast boards. Does anyone from asus even support this forum section anymore?