This would make a lot of sense.
e.g. a single unit does Cheltenham - Swindon, or Hereford - Oxford then couples to another unit to head to London
Could even have a Newquay portion on Penzance trains, or a Paignton portion on Plymouth trains or a Fishguard portion on the Swansea services... so longer services into London, fewer paths needed in the Thames Valley etc.
Whilst that does make sense however on that basis DaFT have seriously over ordered IEP electric for GWML and under ordered bimode..
The way I see it is remote locations beyond electrification are going to be downgraded to core only service...
As an example IEP GWML "core" (offpeak) is supposed to have:
5tph to bristol >
thus
1tph to swansea = IEP bi-mode
1tph to cardiff = IEP electric
1.5tph to temple meads = IEP electric
1.5tph to the west = IEP bi-mode
0.5tph to cheltenham = bi-mode
1tp to worcester = IEP bi-mode
Now I make that only 2.5tph IEP electric's required for the off peak service, for peak it actually gets worse.
GWML Peak
2tph to swansea = IEP bi-mode
1tph to temple meads? = IEP electric
1tph to weston super-mare = IEP bi-mode
1tph to the west = IEP bi-mode?
2tph to worcester = IEP bi-mode
Yet the order ratio is 60% bimode, 40% electric.
Can you imagine the choas of basically a pure 2x5 IEP bi-mode service turning up at reading in the peak which is what will happen if swansea and cheltenham are not downgraded to 1tph and 0.5tph peak respectively.
The bi-modes should have been ordered as 5 car and 8 car sets not just 5 car's for doubling up, anyway out of peak are all the bimodes really going to end up tucked away at old oak and st philips marsh so the eletric's can come out.
In doing so there would be a crazy amount of ECS moves to rid paddington, temple meads and cardiff of bimodes having come from beyond the wires that are not needed until the evening rush.