Stig beve, have you considered the high proportion of passengers that do not book within your consideration of different zone of segregation?
Not to mention that the use of such a term as 'teen class' is rather derogatory toward teenagers and I'm sure that if my partner was booked into this 'accidentally' by answering a question regarding his age, as he uses a 16-25 railcard (And is 17); that he would be placed into a highly inappropriate, loud environment, returning to other segregations...
When I travel with my mother and partner, would I be in the family coach? I know for certain I wouldn't want to be surrounded by families on a service all the way from Euston to Manchester, nor would I want to be in the teen coach, again, due to the fact I'm not a teenager, and never have been a typical one that enjoys making noise for no reason. So this leaves me with the 'business coach' that would likely have a premium attached to the pricing.
Family friendly coaches already exist and have been trialled on VT services between BHM and EUS, a small amount of google for the VT press office will find this; I have subsequently not heard anything about it since then so I can assume it has not been a booming success.
So no, not only do I think it would be a bad idea to escape from the current class system on LDHS rail services because of the evident stereotype re-enforcement it would use, and lack of accommodation for anyone who isn't a teen, family or businessman.
But also it would not work as it would be a removal from the realm of familiarity with the current branding systems available on services, I suspect you'll be on a course that requires you to understand marketing and brand management, so you'll realise just how difficult it is to create a new set of brand values within an existing service where the current vales are not expired, just look at the recent replacement of Tesco Value with Tesco Everyday Value for a perfect example of just how much marketing information (and time) is required to achieve this, and the soft launch used by Tesco in this case would not be possible with services on an LDHS provider of rail services, due to stock rotations and any other number of issues with rolling stock.
So anyway, the segregated class system is a bad idea if ever I've seen one, the UK is not the right place to launch one, and I suspect that the photo's you're using are without authorisation as well, since they are taken on Network Rail property
Out of interest, what MBA / MSc / MA etc. are you studding for this?