As far as the Consett expresses are concerned, I reckon 6356-61 will stay put on the X45 (+ 1 as a spare) with 6362/63 moving onto the X1 to provide the full PVR.
Assuming the X70/71/72 are gonna have to become standalone that would be a PVR of 7 (although part of me did wonder could they interwork with the 12 which is also every 20 minutes) and then the X30/31 would have a PVR of 3. So that accounts for 10 of the MMC's which leaves 4, a couple as spares and maybe 6351 could move to Riverside as the X10 spare allowing 6336/7 to be spares for the other double deck services at Riverside.
Certainly doesn't look like those B5's will be moving off the X21 anytime soon, no matter how many times people post about it
