I've also seen rumours about the class 175s going to gwr so maybe that's the short term plan?
There have been rumours of them going just about everywhere. Nobody that has any knowledge of their “ways” wants anything to do with them and it would cost a fortune in train crew training for GWR to take them. Wouldn’t surprise me if the DfT mandated someone to take them though!
Just a word about unit shortages - if you bend them, Hitachi aren’t liable for any shortfall, neither are Hitachi liable if you don’t get them back to the right depot at the right time.
The 5 car order of 800 units was because the late Stuart Baker devised a timetable that had splitting and joining going on everywhere. He also got the number of sets wrong, having completely underestimated passenger demand at various locations, which is why the 802 9 car order was as high as it was. It saved the DfT from major embarrassment.
The IET timetable and unit workings that the late Roger Watkins and I devised for the GWR December 2018 scheme had very little 5 car working from London on the key routes and, up to COVID, that largely stuck but the move to put the 802 5 car fleet on the Penzance-Cardiff corridor has stretched the fleet. Together with the persistent lack of availability from Hitachi and it is a constant battle at GWR to match resources with demand.