I appreciate the earlier comment that we already have an open standard when Lionel released the TMCC codes.
There is an example from computer processors: the original PCs had 8-bit processors, and now we are at 64-bit processors with hyperthreading and all sorts of cool internal stuff. You would be amazed at the gymnastics Intel designers have gone through to allow a 64 bit processor to understand and run 8-bit instructions internally. So the point is, an open standard, even if designed years ago (Intel from the 1970s) , can be maintained through many evolutions into the future. But, this is expensive: Intel has deep pockets and can support dozens of engineers working for years to develop multiple generations of technology- beyond Lionel's reach to do quickly (a long delay between TMCC and Legacy).
I am not saying TMCC is the "gold" standard. Just pointing out that we already have some of the pieces of these desired future systems right now.
The battery issue is interesting: One idea I find intriguing is to have battery powered locos that have 3-rail pickups and can recharge when running thru or standing on 3-rail track, otherwise 2-rail battery power for the rest of the layout.