They don't exactly have much of a UK manufacturing base left, don't they? However, if their experiment at Widnes proves successful and they decide to start manufacturing trains there again, I very much doubt that will be at the expense of Newton Heath or Litchurch Lane.
Something else that could be factored in to future production numbers is that trains built today will be more intensively used than previously, in an attempt to maximise efficiency. One driverless car is said to be able to replace several human-piloted ones, which might sound concerning if your business is in building those vehicles. However, because each vehicle will be used far more intensively, it will decay faster and require earlier replacement than a vehicle which spends most of its time sitting in a car park. The fact that the DfT is only guaranteeing Agility Trains the use of their trains for 28.5 years, and that Caledonian Rail Leasing says that the market value of 70 Class 385 trains will be £1 after 25 years, suggests that a similar effect will apply on the railway network. Even though it won't be as massive as it is for cars, it will still mean more orders than beforehand.
