I don't think it's a given just yet that GWR will take them on, clearly they still need a lot of work doing to them and that's before route clearance & crew training starts, which could take up to a couple of years. By that time there'll be a fair number of spare 158s available which would be easier for them to integrate into the fleet, possibly also some 170s, so GWR may decide to wait on these rather than taking a chance with the 175s. The maintenance requirements may also be an issue; the specialised Alstom depot at Chester eventually nailed the maintenance regime to make them reliable, but we saw what happened last year when maintenance slipped.