That's absolutely true but I still very much doubt it's so bad that you would exceed 480mbps even on a decent resolution stream. We're not talking multiple orders of magnitude difference. Like... if all else fails just send every frame as a separate image with a fast encoder and you've still got 1.6 megabytes for each.
Steam in-home streaming needs to be realtime too, but is very playable, and most people aren't realistically getting 480mbps out of their wifi.
4k I don't know... 1080p no problem.
Don't most phones have dedicated hardware video encoders on their SoC now anyway?
And don't forget that 480 Mbps is the line rate. Practical throughput to a device will be substantially less, especially if other devices are on the bus.
Webcams need to be very near real-time to be useful. That severely limits what kinds of compression you can use on the video stream.