@H1000 posted:It's a fairly logical conclusion that addition of the 2-way communication (most likely via Bluetooth) will not affect the current operation of their newer locomotives with this feature nor the operating system that runs them. If you buy a new 4 digit addressable engine, it still has to be backward compatible with the oldest TMCC systems out there which do not support 2-way communication. The "talk back" communication from the engine is not required to operate it, it's just a nice add-on feature for those who can use it.
You always strike me as one of the more knowledgeable posters here and I see your point, but sometimes in practice what is logical or what should be the case doesn’t always work out that way. I certainly hope you are correct.