He means that for the mastery challenges we should be rewarded more liveries for locos we own, such as something new for the NEC GP38
Definitely, and the ability to swap between them on the locomotive list. Currently the Class 47 and Class 08 only display whichever route you were on last, it won't allow you swap between them. Of course, allowing all liveries on all routes would be even better...
Would that be realistic, though? Perhaps I'm wrong, but I cannot imagine, for example, a British livery ever showing up on a US or German route. Then there's the fact that liveries come and go over time even on a single route -- don't they? I'm sure forum members will let me know in no uncertain terms if I'm wrong about this.
You misunderstand. I mean if I own the Class 47, I can use the green or blue liveries on the routes it's allowed on. So, Blue on WSR and green on NTP.