Bluetooth

Yes, that is correct. The ability to keep three locomotives in motion simultaneously is a feature of the Universal Remote that is not present in the iOS or Android LionChief Apps.

It would be a good move on Lionel's part!

I've been running 3 engines (battery) with the Bluerail board and my Ipad, I bought a Mad Catz bluetooth controller a while back to see how it would work:

I use it while having my Ipad sitting close by.  The Mad Catz controller doesn't use all it's features (yet?) but control of the engine is fine.  X is for the whistle/horn, B is for the bell.  A changes direction and Y turns the headlight on/off.  The right joystick is for speed as is the left 4-position thumbswitch next to it.  The left most joystick and the triggers on the front edge do nothing from what I can tell, maybe later?

I've said in the past that Lionel and MTH should not tie up their $$$ in command control development, maybe going bluetooth would be way for them to use that $$$ elsewhere.

Doesn't Atlas and 3rd Rail use the (Lionel's) ERR boards in their engines? Maybe I am wrong (won't be the first time or last), but I thought I had previously read that somewhere, possibly even here on the forum??

For the record, as pointed out by Bob Delbridge, the BlueRailTrains system can operate three trains simultaneously from either the iOs or Android app. I do this routinely.