Netflix via playon on the sagetv extenders works on my 32 inch TV, but on the 65 it can’t keep up with CE devices. Part of the problem is that there isn’t any HD content for the PC compared to HD on CE devices.
Knowing SageTV it won’t be open to just one vendor. I would think they would want to go the plugin route so they could support other systems like Amazon video, pandora, etc.