People keep rehashing the same old ideas. To be honest, I think the mix of accommodation is pretty good - double beds routinely sell out a long way ahead, club sells well and classic does too. And trains sell out a long way in advance for popular nights which are essentially Thursdays to Sundays now, plus all the time at half term and on bank holiday and summer weeks. Inverness and Edinburgh portions sell strongly all year round, fort William obviously all summer and more, but Glasgow is not as busy as it was. And the season now runs from Easter to October. Added to that you can buy accessible rooms and seats on every train without having to jump through hoops.
A problem with shared rooms was that people in the know would book them to an obscure station - such as speak bridge - in the knowledge that there was a vanishingly small chance of another person wanting to do exactly the same journey, then carry on to fort William. As a result they would get a solo for the price of a shared room. I don’t think the sharing market is what it was and not are the commercials for it. It also requires a lot more management and has its own modern challenges, such as how many genders should be offered.
Finally it’s often forgotten that, with the mark 3 sleepers, first class was solo by definition. Now it’s not. So, even though some space has been lost due to adding showers / WCs in the club rooms, overall bed count is pretty much still the same.
Oh, and the accessible rooms are a huge step above what was available before.
It’s always possible to criticise, but I think the product mix is pretty close to ideal now. And this is evidenced by it selling out many nights of the year, in a way which the mark 3s never did.