I'm really excited about this S2D and Datacenter scenario.
I agree with JoshRountree, that B&R will most likely be similar to the current process. The nano servers are used for compute and storage clustering, where VMs will be running on top of. So basically only the underlying storage solution changes, the VM itself and it's virtualization platform are not changing. (presuming B&R is supporting Server 2016
Maybe it is a good idea to setup an S2D nano compute storage cluster virtually and try to backup against it...