Our office keeps a pretty separate file structure... with specific things archived (backed up) regularly, and some not at all.
"Word" folder - all "office" (word, ppt, excel, image) documents relating to a project are kept within a specific folder under this. 13001 Documents
"Cadfiles" folder - all cad projects are stored here. Their are subfolders for year, and then each project in it's own folder. Cadfiles > 13 > 13001
There are others, but you get the idea....
When a project is completed, it gets completely removed from the server and is kept only on it's archive disk. We have archive disks that go back to the late 80's, that can easily be copied onto the server for use or documents opened for printing.
Nothing on the server is "inactive" or "complete" because these projects do not need to be part of our nightly back-up.
Every company is different, and the only right way is the way that works for you, but I think you are limiting yourself with what you are proposing.