Thanks for suggesting temporary tracks, I definitely wouldn’t have thought of that and it’s a really cool idea! Ive updated my text on other sites to mention it and link back here.
And definitely agreed on deliberately rebuilding greenways and habitats. I imagine this could happen both automatically (wait and see where people resettle, and what areas are more deserted - probably there’s some deconstruction carried out at the local level, the same way the pyramids and roman roads were scavenged for building supplies) and deliberately (assess the abandoned areas, check their structures for occupancy, draw up community plans for rewilding, argue over it a lot, rezone some areas for greenways/conservation, and eventually bring in crews and volunteers to do the actual deconstruction).