I like to use Duet Display to add some screen real estate to my 13" MacBook Pro. When you connect the iPad with a Lightning cable Duet turns it into an external second screen. Depending on your settings there can be a slight lag, so you won’t play action games, but it works wonderfully for normal tasks (such as writing a book.) It will also translate touch input to mouse inputs and if you have an iPad Pro it also works with the Apple Pen.
I have the 2015 MacBook model, so no Touch Bar and I have no urgency to upgrade yet, even though I think the Touch Bar seems to be very interesting.
So, I am very excited to see that Duet Display added an option to add a Touch Bar at the bottom of the iPad screen). Since the iPad will probably be sitting next to your MacBook screen, rather than right above your keyboard, this is not perfect. But a great way to test an application’s support and see how the Touch Bar works without having to shell out for a new MacBook. This will take away a bit of your second screen on the iPad, but you can enable or disable the Touch Bar at whenever you want.
They have also reduced the price for the iOS application by 50% ‘for a limited time.’ Duet Display uses a Mac or Windows application, which is free and an iOS application which usually costs US$19.99 (now $9.99). Full Apple Pen support which turns the iPad Pro into a retina drawing pad for your Mac is an extra in-App purchase.