You know what is the biggest cost for trains, not the trains it is the tracks. So a smart new business opportunity would be camper train wagon. The Rail companies opening camper parks adjacent to major train links, where people can live in rail campers, a wagon all of their own, one they never need tow, in fact the car can be carried by the same train that is towing their camper.
New lifestyle for a transient population and it fills empty train tracks with more traffic. Need to shift you rail camper, just book it in, quick tow to junction and they hook you up, load up you compact car which no longer needs to pull a caravan and away you go to your new rail camp site, dropped off and away you go. You can travel in your camper, watching the country go by no muss, no fuss and depending on design it could go high speed.
Filling empty train tracks with a major business opportunity. Likely though light weight carriages need to be design along with a lighter engine and they simply use the track between normal passenger and cargo trains.