What a great idea. Ok, it was only a matter of time before something like this came on the market, but over at Red Sweater, an application has been developed that mimics the new Touch Bar, available on the latest MacBook Pros.
Touché is superb! When you run the application, you will see the image of a Touch Bar appear at the bottom of the screen. As you open applications that are compatible, the available shortcuts modify to reflect the app. I tested this straight away with Airmail and was pleasantly surprised when the Brightness, Dashboard and Mission Control shortcuts were replaced with New Mail, Synchronise, Filter and the like (as well as an Esc key on the far left - nice touch!).
It's great and remarkably, it's free. I would recommend sending a donation via the site though.
If you would like to see how a Touch Bar on a new Mac would work, you could do a lot worse than download this wonderful app.
Get it here