The problem with smart ticketing on the National Rail network is that government and politicians view it as a panacea for "passenger choice" and also a means to demonstrate modernity and to cut costs of ticket selling. They look at Oyster and think it means instant massive ridership gains, more money in the bank and lower fares. All of this ignores the nature of transport and business activity in Greater London and the sheer density of the transport network.
I recall one comment from Shashi Verma, TfL's Director of Passenger Experience, who is responsible for Oyster. He said that one reason why Oyster is very complicated "under the surface" is that it was built upon a load of old and longstanding commercial rules. Clearly some other rules were junked, e.g day returns, when PAYG was introduced. That to me is a key point so far as the NR network is concerned.
What are trying to do? Who are you doing it for? I am deeply sceptical that you replace paper ticketing with some form of "smart" technology without severely affecting some of the key tenets of NR ticketing like the basic fare structure, break of journey, split ticketing, combined rover and single tickets etc. London has abandoned or does not allow some of these rules. People need to decide if the loss of some convenient facilities / rules is worth having a piece of plastic that can "talk" to the internet or something "virtual" that is recognised on their mobile phone.
At the end of the day you can design anything but the burden of supporting technology and mandatory action / compliance on the part of the passenger may be too much. Many years ago I used to understand NR ticketing but I have really lost the plot in recent years because of the impact of routeing, multiple TOC specific products and easements. I am deeply sceptical that railway staff and passengers have any sort of realistic prospect of keeping up with the current product and pricing structures and associated rules. That is not to criticise any members here btw - it's just an observation about complexity and the never ending pace of change.
If you were prepared to start again with a clean sheet of paper and were also prepared to fund a massive change in equipment provision then yes you could have smart ticketing on a nationwide basis. However you would probably lose a lot of what people have today in terms of some of the flexibility that dates back many many decades. I doubt people would agree to that though once the implications were understood.
I don't think the current proposition for "smart" ticketing, as recently explained by Roger Ford in Modern Railways, stands a chance of working. I think some people in government and the industry have been dazzled by a technological proposition that has too many potential "points of failure". The failure to deliver SEFT tells me that the fragmented structure of the industry is also a fundamental problem (e.g. commercial confidentiality, data ownership, system ownership). If you can't do SEFT then how on earth are you going to get a similar scheme introduced anywhere that works seamlessly?
I will sound immodest but given I worked on designing what became Oyster in London I could probably, with a fair wind and a lot of learning, come up with a smart ticketing proposition for National Rail but it probably would not replace all paper ticketing.