I wonder if anyone is working on making double-layered carbon nanotubes where the outer tube has a ringed structure like microtubules or nodes of ranvier to act like neurons. That'd be cool.

Is there actually any practical application if they do make such a thing?

They're much lighter than traditional wire

to add to that lightness makes it a good candidate for using as overhead power lines in electric grids, currently they use aluminium instead of copper precisely because it is lighter so you need less pylons but the tradeoff is worse conductivity.

Good! It'll be worth more when I tear it down and sell it to my local junkyard guy. /s

Probably transfers electrons much more efficiently.

So useful for everything from high voltage power transfer to data cables.

Yet all they must do to solve the issue is CONSTRUCT ADDITIONAL PYLONS.