I had this idea that there really is no reason why the Touch Bar interaction couldn't be done in software and a wireless connection to an iPhone or iPad. Perhaps Apple will implement something like this in the future, once the Touch Bar idea becomes more accepted. Macs and iOS devices already have something similar to this in Logic Pro X and the Logic Remote app. This app creates a touchscreen bridge to functions in Logic. It's really quite advanced. It was exclusive to the iPad, but they have made an iPhone version that is really quite handy. I don't see the Touch Bar doing too much that couldn't be replicated in this sort of software. From reports it the Touch Bar is already running a version of watchOS and interacting with the macOS. The only issue I could see is a bit of lag, but it's mostly just buttons. And they already have something working for Audio applications, so lag probably isn't a huge problem. It would never be as convenient as having a Touch Bar on your laptop itself, but as a compromise or a feature for the desktop users it would be pretty convent.