It would be nice to export a web map as an XML file, similar to how you can export an XML Workspace Document from a geodatabase. Conversely, having the ability to import an XML to create or update a web map would be great. This could be used for backing up web maps, with all of the layers and services and pop-ups etc. Currently I have had to rebuild entire web maps if I change the properties of one of the services in the web map, and it is a bit frustrating. Other than an XML, maybe a file that ArcGIS Pro could create, from a web map, and edit, then update a web map with the edited file.