Will ticket prices now become "malleable"? Will the customer be offered dozens of coupons, or a through ticket on one piece of card, simply with the price reduced?
The implementation is unclear at the moment and I'm struggling to get my head around it.
Do you know how Advance tickets work? If you do, it helps a bit.
The way they work, AIUI, is that each route is split up into segments, and each segment has a set of quotas.
So as a simple example, we have London to Manchester. That might be split up into a segment London-MKC a segment MKC-Stafford, and a segment Stafford-Manchester. (It'll be more than that, but let's keep it simple).
Let's say each has 2 levels of Advance fares, and that means each segment has a quota A (cheaper) and a quota B (more expensive). Each contains one ticket.
So we have:-
EUS-MKC: A 1, B 1
MKC-STA: A 1, B 1
STA-MAN: A 1, B 1
Somebody comes along and buys an Advance for MKC-STA, and therefore use the A quota up for that journey. Now, we have this:-
EUS-MKC: A 1, B 1
MKC-STA: A 0, B 1
STA-MAN: A 1, B 1
Somebody then comes along and tries to buy an Advance EUS-MAN. At present, quota A is unavailable for the whole journey, so it has to come out of quota B even though quota A is available for EUS-MKC and STA-MAN.
You can see how that could cause a problem, particularly if it means no Advance available at all, or if the fare B is much higher.
The fix to this is that each segment is treated on its own, and the fares are summed into an overall Advance ticket issued on one coupon. This could be implemented in lots of ways - by splitting fares down by distance, by having a fare per segment, simply summing the fares STA-MAN at A, MKC-STA at B and EUS-STA at A and if it's cheaper than the through ticket at B using that as the fare, and probably others. I don't know which they intend to use, but I do understand that fixing this particular problem is the basis of what they are looking to do.
With regard to off-peak walk-ups, I don't think they are doing anything specific with those other than tidying routeing up and going for single-fare pricing. The problem with off-peak walk-ups is that it is basically impossible to have no anomalies. The only way to have no anomalies is therefore to abolish them - or just to say if you want to be absolutely sure you have paid the cheapest fare in a simple transaction, an Advance is the way to do it.