Just as a fun thought experiment, what /new/ things could be possible if we had 1Terabit/s?
honestly, it's more than enough to have 50 TVs streaming Netflix or YouTube, the computers downloading stuff, phones being used and so on.
I am really not sure how 1Tbit would even matter for 99% of the population. Maybe if streaming (actual) 4k became a thing. Perhaps for remote-gaming, but latency would need to be very low. I cannot imagine the latency on a train.