Here are a few ideas I have had bouncing around in my head the last few days:
1. I really like the idea of incorporating a video feed from the various cameras into the Cab3 app. The next iteration would be to have the app screen image of the interior of the locomotive cab (and windows looking out) with controls (throttle, brake, whistle/horn, bell) so you could operate the loco with prototypical (albeit on a screen) levers, valves, meters, etc. while being able to have a first person point of view forward from the cab via the camera. How fun would it be if you had to monitor boiler pressure, water levels, fuel usage, adjusting for an incline, etc. while viewing your layout from inside the loco cab?
2. I'd love to see the ability to send the engine sounds to a separate sound system via bluetooth. This may or may not be possible with the Base3. It would be nice to send the sounds to a system/speaker/sub that could handle lower frequencies that the small speakers are incapable of. I think the loco should still provide some sound so you can get some sense of audio locality, but the lower omnidirectional frequencies could be handled by a subwoofer below the layout.
3. Another fun idea is to have different user interfaces for accessories. For example, once you select a gantry crane, the interface would look like the control panel for a gantry crane and you would use those levers and buttons to control the crane. I think the flexibility offered by an app based remote is a real advantage moving forward.
4. @Dave Olson thanks for all of the hard work you and the Lionel team put into this new system, while maintaining complete backwards compatibility. I think you all hit the nail on the head with this one.