That's something that seems like would be feasible in a more monolithic world of broadcasting, and smaller firmwares. They could probably simply broadcast various firmwares at different times; then if the TV detected "hey, that is for me", it could capture the packets.

It's hard to imagine streaming services like YouTube, NetFlix and whoever agreeing to do anything of that sort.

Indeed, my guess is right about this seems to be in the right ballpark:

https://en.wikipedia.org/wiki/Data_and_object_carousel

If you're still relying on DRM functionality, a DRMed source could suddenly demand you upgrade the firmware and refuse to work until you do.