Although Daniel Mersey has not produced expansions for any of his Osprey "N-Rampant" games so far (...that I know of?), I do hope that XR does get one and that it focuses more on vehicles of all types.
I understand the focus of the main game is on (roughly) a platoon of infantry, and that vehicles are in support/incidental to that, but I really do think a few more classes with different options would be well-received.
I also wouldn't mind some slightly more detailed vehicle rules, and as there's normally only a few present, I don't see these slowing play down.
Such an expansion could also have some alternate force compositions for running more vehicle-dominated forces too, and perhaps even a few additional scenarios made with vehicles in mind, or where the vehicle(s) is the main part of the scenario.