the DD's need mid life refurb now, the mk4 will need it in 10 years (they need an internal one now) so its much of a muchness.
as mark says they are not cleared to operate in NI but that is something that can be achieved with a bit of willpower and initiative.
there is no real plan at all, or any plan is changed/abandoned because of things.
we attended a big think in up in belfast a few years back (4/5???) with all the stakeholders. everyone agreed that it should be an hourly service and it should be attractive.
only thing done was to try and convert the electrical vans from Mk3's to be put into the DD's and even that was ballsed up and took forever.
I would imagine the next solution will be ICR's. Those who use the first class bit of the Enterprise will be in for some shock. No matter how you dress it up, in my experience the 22ks are an inferior product to the DD's and the Mark4's. (yes, I know about the windows).
Even if you do not agree, taking trains specifically marketed and branded for a service and replacing them with common rolling stock and then cutting those trains in half only sends a big subliminal message out there to the public - you aint getting what you once had, and here is a fare increase. Cheers. What do you mean you're taking the car???
We are the passengers