Better ask the DfT nicely to fund the various clearance tests to ensure the Mk5 coaches fit on the XC routes, the funding to train all the staff up so they can operate the stock + loco. The likelihood of those things happening is low.
And also ask DRS nicely if they will be willing to enter into another agreement to lease the 68s which they are already using on various freight work.
Off course, XC could solve overcrowding on the Reading - Banbury corridor by not serving Oxford

.
The current timetable doesn't help when a XC departs Reading a few minutes in front of a GWR for Oxford, so any customers at Reading wanting Oxford will squeeze onto the voyager as it's the first train init. Likewise at Basingstoke where the Manchester train generally departs around XX:47 which soaks up a lot of the Reading passengers whom would otherwise use the XX:52 GWR service.