I am a little confused by your response... I was there with you until you made the comment about reading speed and then discounting the benefits of higher speed due to 4k market.
First of all, at 270mb/s SD looks absolutely frigging awesome. Raw SDI signaling of SD video is truly amazing. I used to work a lot with film masters and often watched in original quality and it was insanely better. Higher frame rate is better. I recently saw raw 4K footage (which is heavily compressed since no one records at 12Gb/s) and raw 2k footage, both on 65" screens capable of 4k from 2 meters. Guess what? No difference.... Well until I looked at test signals which showed line art and hatch patterns.
4k is just not interesting outside of movie theaters.
So... 10Gb/s business case. To start with... Because we want to know if we can. For the moment, 4k is the only use case. At the rate which technology is evolving and the world is using it, real-time broadcast becomes less interesting except for sports and emergency information. So, we don't even need 10Gb/s for video.
Where can we use it?
- Offsite hard drive storage
Not so interesting since Google is also building Chrome which idealistically would run the app in the cloud too, so you only need bandwidth for remote desktop type of transfers.
- Remote gaming
Because running high frame rate games remotely is laggy, so eliminating latency issues with brute force instead of QoS makes sense. After all, QoS only works if you extend the trust boundary to the client which would be a nightmare.
- Video conferencing
Works pretty good at 384kbs in most cases, 9mbit for awesome quality, so even DSL should be fine. Most issues now are at the endpoint, not the network.
Honestly, I have no idea what the business case for 10Gb/s are. I personally don't notice the difference between when I'm on 1gbit at home or at a customer who has 40Gb/s access. The issue tends to be that the servers I connect to aren't fast enough to handle the load.
P.S. Downloading a film on iTunes from a PC with a 10Gbit NIC and a 40Gbit Internet connection rarely gives me more than 3Mbit rates.