I don't think there's any guarantee that a v8 will be upgradable to a v9/10 supporting Atmos and DTS:X. It all depends upon how / if it is implemented but considerably more processing power will be required somewhere. If the 861 is the target for extra processing power then it’s a distinct possibility that a completely new architecture will be required.

It could also be a long wait so I would consider your options carefully.

Main system - Sources (Kodi-HTPC, Vero 4k, FireTV, Sat) into Trinnov Altitude 32 (8-16) (+Roon), Trinnov Amplitude 8 amp & Vivid Audio (Giya G3, V1.5) and REL Stentor III speakers. Others: F80 + Raspberry Pi and other Pi systems.