If rail services are to follow airline methods, I presume the same approach will be taken about breaking up the seats provided for different categories of passengers. You can regularly find this on airlines where the cheap fares are just never offered where they think it the flight can be filled by others who may pay more.
For a multi-stop train, the same approach will be with lesser journeys. Try and book months beforehand for the week before Christmas for Doncaster to Grantham and there will be nothing available - all being kept for Newcastle to Kings Cross and similar journeys; we don't want to turn those away just because all seats have gone for bits of the journey.
Incidentally, one can notice that multi-stop airline flights have pretty much disappeared, virtually all now are point-to-point and back again. One of the reasons was the commercial and operational downside of parts of the journey not having enough passengers, where other bits are oversubscribed.
For a multi-stop train, the same approach will be with lesser journeys. Try and book months beforehand for the week before Christmas for Doncaster to Grantham and there will be nothing available - all being kept for Newcastle to Kings Cross and similar journeys; we don't want to turn those away just because all seats have gone for bits of the journey.
Incidentally, one can notice that multi-stop airline flights have pretty much disappeared, virtually all now are point-to-point and back again. One of the reasons was the commercial and operational downside of parts of the journey not having enough passengers, where other bits are oversubscribed.