I suspect that next year, some of them could replace the Class 170s in South Wales, releasing them to East Midlands Railway.
In the medium to long term who knows!
That could work. No doubt the 170s are in higher demand elsewhere than the 175s. The Flirts are currently being tested but I'm not sure if they are tri-modes for the Rhymney or Bi-modes for maesteg/Ebbw which will arrive first and when they will be in service.
The only problem with the 175s is needing up to 8/9 units based in Canton with the maintenance still needing to be done in Chester. That would mean over 16/17 units being based in the south out of a fleet of just 27. Its also reliant on 197 deliveries, as the Flirts could well be in service by the time a sufficient number of 197s are delivered to release 175.
If I was TfW I would be holding ok to the 170s until the Flirts arrive and using spare 175s to cover Crewe-Chester and West wales to free up some 150s and 153s.
I can also see the 175s staying slightly longer than everyone thinks.