Interesting. So this is how Apple will use its ARM prowess to improve Macs in the future. Maybe we'll see the MacBook Pros start offloading basic functions to ARM chips in a future model, freeing up the Intel chip for applications.
iPhone 7 has a quad core architecture, two very powerful cores and two running at low energy, but they're all ARM.
I don't think they'll realise something similar with two Intel cores and two ARM for the Mac, looks like a ton of work and macOS should run on both architectures at the same time.
The touch bar is managed as it was an external device, so T1 can be used. Maybe in the future they'll add functionalities and managed them in the same way, allowing the T1 or other SoC to do all the work instead of the main CPU