The new Northern trains are planned to be leased. Any savings would be operational/resource spending not capital as a result and spread across many years. It doesn't free up a pot of money for infrastructure.If 37 350/2s are being transferred to Northern, that will save a new build of electric units saving the Treasury say £250 million? That £250 million should be spent on further electrification such as Windermere branch, Carnforth-Barrow, Wigan-Southport or Ardwick-New Mills where 350/2s can displace old diesel units.
If anything short term costs will increase and it will be future years where the saving is realised. The industry needs to save money where it can and has challenging targets. DfT operator has a target to reduce net subsidy by a further £200 million this financial year alone despite the fare freeze.