Just a thought/sugesstion:
I have some notes that I no longer need but don’t want to delete. I’d like to archive them as I do with all my emails as I may need them in the future. Currently, AFAIK, there’s only an option to move them to Junk. I know you can restore notes from Junk, but still, it’s called Junk so I’m not really sure if notes stay there forever or just for some time? (If notes do stay there forever, maybe you should rename it to Archive?). Maybe, you could count cards in the Archive towards the free limit as well.
Also, once I add something to Outline I don’t really see a way of removing it from Outline.