If it ever comes, it won't be for Console only. Stop putting "for PS4" or whatever behind your request. A DLC will be made for all platforms, or not at all. Also, could you tell us a bit more about your proposal, please?
You might want to aim for the suggestions part of the forum. Also don't say for ps4 & xb1 because all add ons are going to be on PS4,Xb1 & PC. Also we have moved on from TSW 2020 we now have TSW2. Just some tips but yeah a P42 would be nice
Amtrak service over Sandpatch seems like a natural fit. Would require locos and rolling stock (not sure what's being run there, Viewliners maybe?)
Typical Consist of Superliner I and II cars, and the Viewliner Baggage Car. Superliners have been on service on the line since 1994. But as far as the P42 is concerned, I say the earlier the better. As this way the P42 can be added to the timetable to any future routes that feature an Amtrak LD train that has P42's in regular service. An example is the upcoming Cane Creek Route, while its unknown if the route will have part of the mainline out there, The California Zephyr could easily be added to the route as part of the timetable for the route. (If there is enough of the mainline for it to run on, even if only as traffic.)
A P42 would be great to have. Like Blacknred81 said, the it could be added to new American routes that have Amtrak services.