I just stumbled accross this whole subject. Very interesting.
The major point I have not noted folk discuss in the posts is that with bluetooth you should be able to reliably transmit control packets much more efficiently to a loco instead of relying on poor connectivity as the wheels trundle along the track. I get frustrated in how often my locos ignore commands and merrily carry on full steam ahead to crash into whatever obstruction you are trying to avoid!
One of the other trends in posters initial comments was the idea that the settings would all be stored in a phones app. Well with bluetooth I see no reason why they should not be stored in the decoder itself, then when a handset pairs it would pull down the required settings as and when required.
Indeed as for sound I see no reason why the controller could not simply stream audio to the relevent lococs, after all I tend to store my music on my phone and stream it either to my in car audio or blutooth speakers nowadays, gone are all those silly CDs.
However just like DCC I find once you have more than a few locos on a layout that trying to toggle them all is a nightmare.
I have made a few abortive attempts to write my own software to drive my Lenz based system to no avail. All I would like on my computer screen is a grid of several cabs so I can quickly control 8 locos.
That said I have just dismantled my Leviathan of a layout and boxed it all up for the forseeable future (including my Garrett).