I suspect the answer is, some of the features of 2.1 are potentially available via firmware updates, while others will require a hardware change. For example, I will be very surprised if the current chips support passthrough at the 45 Gbps speed defined in the 2.1 spec. (In the Lumagen Pro models, a hardware change is required to go from 9 to 18 Gbps.)

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.