I was having a similar thought the other day, and the thought came to me when, as we were circling over Liverpool on the way in from Amsterdam the cabin crew were making their usual spiel, and then they thanked us for flying EasyJet and "we know you had a choice of airlines today". Well, the idea of privatising the airlines might work as something of a model. I know that there are substantial differences between running planes and running trains. But there might be some chance for an overlap.
There is a lot of demand for travel between Amsterdam and, say, London. And in response to that, there is a lot of competition. And each airline has to offer something slightly different. KLM for example give you free luggage, great if you're going to transfer to a long haul flight. EasyJet might offer you a dirt cheap flight, and gets you in early enough for a morning meeting. British Airways might offer you the best choice of flight from the airport in London closest to you. And Ryanair might dump you in Gronigen and claim it's Amsterdam, but only charge you £1.50. There are a finite amount of 'paths' through the airspace between the UK and mainland Europe, and each of these airlines bid for these slots into and out of each airport, and the airspace in between, each to cater to a different market. So why not apply the same to the core routes on the railway? Under the present system, there is very little direct interaction between supply and demand. And there's a pretty good analogy. Between Crewe and London there are two choices: Virgin and London Midland. Both offer very different services. Virgin: quick but quite expensive. London Midland: slow, but cheap. I can now use my 'vote' and say that I want a supply of cheap seats on a train that offers something different. I rarely have to be in London first thing in the morning, so I don't need to pay a premium to get there in 1hr30, and I am happy to pay £10 and it take 3hrs.
This type of competition is beginning to creep its way into the railway market with the various Open Access operators running on the East Coast, and we should welcome more of this from a more even keel. So effectively remove the dominant position of East Coast on running the services.
So I will admit that this is fine for the core routes, for example between London and Amsterdam. And I have never been on an anything but full flight between those two locations. But look at the example of the Highlands. I'm reasonably certain, and I am open to correction, that some of the flights between the Highlands and Islands operate only with the application of a subsidy from the government. At certain times of the day, these flights will make a profit. In the same way that the route between Norwich and Liverpool will make a profit, and at other times of the day it won't. So, you offer some form of incentive for an operator to run the service. This could be in the way of no track access charge, or just some form of direct subsidy, much in the same way that exists today.
A total hand over of the railway to the principles of the free market should probably be refused, but when the market for air travel took off (sorry...), it didn't mean the end of vital community air routes, like those between the Highlands and Islands, and many other examples round the world.