I think the main difference between questions/answers and edits is, if you write an answer or a question, its yours. No one else but you can edit it at that point, so its no problem if you want to continue your writing after some hours.
If you have an edit, you work on an existing post (even if its yours), means other people than you can also edit. Especially when the post is worth editing, and you want to take a break for some hours, I think chances are good that the post has changed since you started your edit and in my opinion it would be not appropriate then just to finish your edit and post it, overwriting the previous edit.
So, what should happen if your edit is saved, but the post has been edited in the meantime? Maybe the post has been clarified and your "old edit" would have a different meaning now (maybe not if its your own post). Then there should be some kind of diff where you can compare the current status and your edit.
My idea would be bit different:
Give us an advanced editor!
I would like to have an editor (similar like now but opening on its own side/tab), with
a bigger edit field
a bigger preview, maybe on the side of the edit field (better overview on widescreen monitors)
The possibility to save drafts in my account (more than one!) ==> this would be the answer to your question.
With a button in the inline editor window to copy the current content to the advanced editor.
This would be big improvement for writing good, structured posts, that take a bit more time to think, because they are not FGITW answers.