So presumably there would need to be additional seated carriages available to have through coaches as well.The combined traffic to Fort William and Aberdeen from London doesn't justify two lounge cars and two seated cars and each "set" is standardised on having six sleeping cars, one lounge car and one seated car.
Would be nice to have sleep pods or something something affordable while having a bed. However if the berths sell and the trains are as long as they can be, plus the fact the new rolling stock is just in and teething, it's difficult to see something like that happening anytime soon.
Seatfrog would be relatively easy to implement of course, while to be honest bringing back shared berths should be considered. Those that want their own cabin can pay the standard price, while having the option to pay 60% of the price or so to share with a stranger. Is there any commercial reason not to?
These should make beds a bit more affordable, and even available, without simply making things cheaper for customers who would already have used the service.