The unfortunate underlying issue is the API pricing is by and large not sustainable. Even if a third-party application has not announced they cannot continue operations, the lack of announcement does not mean they plan to or continue. I can see the want of biding time and waiting in this circumstance, but ultimately I don't see any third-party application staying active in an above-board manner if the API pricing is launched as is.
Apollo, RIF, and Sync announcing they are shuttering adds additional pressure to the matter.
Reddit doesn't (at least as far as I know) store a history of edits, so what is saved on the database is what your comment literally is. The reason people suggest overwriting comments is because the comment itself has value (for a variety of reasons), so overwriting the comment with something valueless (in the sense that it has no value for Reddit) is better, so the database itself is updated with that valueless comment.
After that whatever you do with the account is up to you.