IMHO digital entertainment doesn't make up for being stuck in a cramped cabin for up to 19 hours (the longest international flight) around people (with varying levels of considerateness, contagiousness, and personal hygiene). Not to mention the increased risks of DVT and radiation exposure.
I travel each year to see family abroad, a minimum 2-leg trip totaling at least 27 hours. I can't sleep on planes so I arrive exhausted and am useless and cranky for the first 2 days after this trip. I would happily pay 2x the fare to cut that trip in half.
If you're flying half-way around the world, sleeping on the plane or a shorter flight isn't going to help much. I've done it twice and the jet lag is killer for the first 2-3 days regardless of how well you sleep on the plane (I usually sleep very well).
Deep Vein Thrombosis?
If you can afford supersonic travel, then you could also afford first class. And supersonic travel will probably be like flying economy. The concord was pretty crammed compared to today’s first class.