Quick googling suggests 4k needs 25 Mbps, and 8k would need ~100. Seems like another limiting factor is the consumers internet connection.
Bitmovin can do 4K video on demand at 2 Mbps with AV1:
https://bitmovin.com/per-title-encoding-savings
Live, low latency video can't achieve the same because it can't use all the encoder tools due to time constraints.
But Cisco was doing 1080p30 video calls with AV1 five years ago:
https://blogs.cisco.com/collaboration/cisco-leap-frogs-h-264...
They said they were surprised at the number of encoder tools they could make use of in AV1 for live video and that it's all about making smart choices in your encoder for your particular use case.
Live streaming games at 4Kp60 with AV1 can be done at 6 to 10 Mbps:
https://insider-gaming.com/how-av1-encoding-is-bringing-stre...
So for distribution with AV1 you'll get significant bit rate savings and you won't need anything like 100 Mbps for 8K.