Question - Atlas completion transitioning to 3.1

I'm planning on mainly playing standard in 3.1 since I don't have the time to keep starting from scratch each league but I'd like to know how our atlas completion is going to work transitioning from 3.0 to 3.1? Will we still have all the maps we've completed in the current layout completed in the new one even if the map changes tier? If so we could end up with lots of red maps completed that we don't want to drop. I appreciate that GGG are trying to incentivize running a varied map pool but if I have to un-complete a bunch of red maps to get my atlas how I like it I'm out.

As I understand it, any map progress you've made will be available to characters you start in Standard or which get merged into Standard in 3.1.