My idea is that, similar to the livery designer you will be able to create consists without limits and like the scenario planner there could be a realism feature that is toggle-able. With this feature you will be able to create whatever consists that you like for ones that aren’t already included in the scenario planner such as class 35 top and tailed with Mark three coaches. Or more unorthodox formations like an ICE hauling NTP freight. This would allow us to get the most out of our purchases.  in addition to all of this a consist creator will allow us to haul longer consists than we already have, and allow us to finally rid ourselves of those awful menus that half the time don’t give you the loco you want (lookin’ at you BR green 47).