I think it would be nice to be able to access system events like monitor added, and monitor removed, to be able to implement things like, save window positions before a monitor is removed (if possible), and restore window positions when a monitor is added.
Maybe a whole new category for monitor and window management.
I often change from 1 to 2, or 2 to 3 monitors (and reverse) and sometimes the windows are not restored back correctly by the system (or the way I would like to).
I know there are tools out there just for that, but I think none of the current ones addresses the problem correctly, and BetterTouchTool has become much more than a touch tool.
Just an idea to improve the tool, now that it looks like the touchbar has not much future.