Maybe if the touch bar detects any touch on the very left side it will activate the escape function? No one knows how everything will work until real people get their hands on it since no reviewer has mentioned it.
One can assume that the people working on this inside Apple use the escape key, especially if they worked on the Xcode integration. I'm going to make an educated guess that the escape functionality will work perfectly fine and only super OCD weirdos will have a problem with it after using the actual things for 5 minutes.