Those new trains are actually trainsets, fixed consists of 7 cars, with the intention that the locomotive stays coupled permanently too (like the Railjets). So they cannot easily change the compostion.
i think the pods are a great idea. They have still a few bugs to iron out, and I wonder if the maker of that video knows the secret of getting some sleep on a night train: ear plugs.
I travel by night train semi-regularly. I have a customer in Vienna, and will often take a day train there on monday, to spend a few days with them on site, and take the night train back on thursday. Recently I took the night train both ways, as I managed to get a deluxe single outbound.
The thing that bothers me a bit is the changes in the prices. The new sleeping cars are nice, with all compartments now having en en-suite, but the pricing is now so that as a single traveller I have only the pods as a reasonable option.