Not having a fast through service from London to Glasgow and vice versa would be the absolute demonstration of a dysfunctional railway. That, I'm afraid, is an unbelievably terrible idea.
Well the Japanese model is to break services like this when high speed lines are constructed.
It would be a radical break with the previous concept of through services to everywhere, but I don't think it would be that damaging to the image of the railway.
The public can plainly see that things really aren't going well.
So is this proposal just a WCML upgrade, with the scope to improve and relieve ECML, MML and XCML abandoned? It feels like it would be a massive own goal if that's the case and would massively hinder future upgrades.
The genius of HS2 is that on one core route into London, it could cover all four of those mainlines, with Birmingham to Yorkshire & North East seeing some of the biggest benefits. But that only worked because it was seriously fast, which meant that it was quicker than existing ECML and MML services despite having a longer route.
I'm not convinced HS2's concept was ever truly workable.
It required pushing a load of technologies and operations to the absolute limit of what was achievable, and despite several attempts noone seems to have been able to come up with an actual workable design for Euston.
Sure, replacing all main lines with one sounds good, but the actual implementation has some serious limitations. For example limits on service cuts on the classic lines from the need to serve intermediate stations, and questions about economics of the slower services once the high paying long distance traffic vanishes.
I don't think they should have ever have attempted such an ambitious scheme, especially given the questionable phasing decisions that were made.
HS2's management also appears to have a unclear and constantly changing view of the line's role, which didn't seem to have helped matters.
If the line between London and Birmingham is only specced for 155mph then it's unlikely that it could be easily upgraded to higher speeds later, which means that it is unlikely that the full Y could ever be built, because there would be no demand for trains from London to Yorkshire & North East that were slower via Birmingham than on the existing mainlines. So any additional capacity or accelerated journey times on that axis could only be achieved through building a second high speed line into London, which would almost certainly be prohibitively expensive.
That would sabotage the future of long-distance rail in this country for generations.
The line is going to be specced for 360kph, its already half built!
Given the runaway budget increases on HS2, continuing with the HS2 concept is going to be prohibitively expensive!