Wrong way to think about it...never will "all passengers" be doing something. Same as any network (ISP, IDF closet, cell network, stadium, department store, etc.), you plan for oversubscription. Think 10:1 oversubscription for a starting point. So 180 passengers > 18 active users > 20mbps per active user. An airplane may have more active users if the service is free...

A network that is not oversubscribed and provides full non-blocking throughput to downstream devices is by far the exception: high-end datacenter spine/leaf systems come to mind as an example.

Using the current fleet of Delta Air Lines as an example[0], they average ~180 seats per plane. If everyone on the plane was using the internet then that would be 1.9 Mbps per passenger. GeForce Now requires 15 Mbps for 720p 60fps[1]. If there was no other internet usage then 350 Mbps could support 23 15 Mbps streams.

[0] https://en.wikipedia.org/wiki/Delta_Air_Lines_fleet#Current_...

[1] https://www.nvidia.com/en-us/geforce/products/geforce-now/sy....

Personally I feel that plane WiFi doesn't need to be that fast. If they can make it more reliable (especially over water) and with lower latency I'd be more than happy with it. I don't need to stream YouTube.