I doubt that the class 379 units will be used by GWR. However, I can see the 29 class 387/1's with Great Northern being replaced by the 30 class 379 units, as there would be little paintwork required on the class 379 units. Great Northern would still have 7 class 387 units in the shape of 1 class 387/2 and the 6 class 387/3 units if the details within
https://en.wikipedia.org/wiki/British_Rail_Class_387 are correct. I don't believe that the details are correct, as it is not showing what has happened to 387202 - 387204.