I would like to be able to create folders within projects to help better organize my projects.
For example, at the moment I am working in a Project that I call "Board Maps". This is the project I use to create various maps (in layouts) that I export out to images to eventually insert into Power Point slides which show up at our board meetings. We have board meetings quarterly. I would like to create a folder withing my Layouts in this Project by quarter so something like "2018Q1", "2018Q2", "2018Q3" and "2018Q4". I may have the same layouts referencing the same maps in each or I may need to make separate but very similar maps for each quarter - which is why having the ability to replicate my folder structure in the Maps part of that project would also be important.
Some Layouts and Maps would be universal and those would exist in the "base" folder directory.
I've already suggested adding dates to Layouts and Maps which would be helpful but having Folders within Projects would help keep users organized and feel somewhat familiar to folks migrating from ArcCatalog