On board catering should have a future, and should be looked at as part of the service rather than a profit centre in its own right, i.e. break even operation.
Howver the reality I suspect is different.
TfW seem to think its a useful addition to longer journeys, other operators are less enthusiastic.
My own view is any journey over 2h should try to offer at least hot drinks and snacks, even if its a hop on hop off trolley covering the core part of the route. Anything at 3-4hrs or more should be offering something more substantial.
Watching a video about Indian Railways there was mention of a take away app where food is delivered to the station and direct to the passengers, maybe something like that could work in this country. Maybe trolley host takes the orders and its delivered to the next suitable stop, and taken to passengers.
It feels like its one of those areas where there has been no imagination shown. My own 'recipe' would be keep it simple, popular and cooked fresh where possible. Its a shame someone cannot design a deep fat fryer which is safe to use on a train, Fish and Chips would probably tick those boxes. Maybe each train is fitted with a different 'fast food' kitchen so regular travellers get a change.
Proper multi course catering is good but can only feed a small proportion of full train, maybe see how the TfW model works out. Also cost would probably rule it out for a lot travellers.
What is needed in my opinion are simple hot dishes that sits between sandwiches and full blown 3 course meal.