Flights of Fancy. I wonder ... ...

[Dorsetmike]

 ... how long it will be before somebody takes digital to the next step?

Digitised crew? Driver and fireman with contact pads on their feet so that either at set intervals or from a button press and the fireman swings his shovel and the driver moves the regulator, maybe the movement intervals could depend on speed setting; of course this would be coupled with digitised smoke which as well as coming in puffs  the rate of which depends on speed setting, but also the colour changes from white steam/water vapour to dirty black smoke with smuts when the fireman swings his shovel.

Guard sticks head and hand out of window and waves flag, acompanied by whistle sounnd. before starting

I can see it being just about possible in 0 gauge, and posibly 00 if miniaturisation of servo components to fit into crew bodies progresses enough.

Porters trundling barrows could be another possibility, but I can't see animated pasengers getting into carriages.

At least none of that would be as irritating as the noises from a diesel layout behind one for two whole days at a show

[austinbob]

Interesting thoughts. 
Probably not worth it in N gauge all too small. I can't make out some of the existing N gauge detail on a moving train, that's why I never bother with the detail packs.
Here's a thought. Everything you described can be much better observed on a full size train. So off to your local heritage railway and get a fix there.