Two things would have done it for me. They could have offered a user token subscription that I could port to all my accounts. Sure there could be token sharing with that method, but for a “modest” user cost, I might have been tolerable of it. They would have had to open the third party apps at the same time, but it would have bought time. The second thing would have been extending advertising through the third party app. That might discourage users of the free third party app, but it would also have given time to readjust the market price. Maybe the compromise would be that the free app could still be free of Reddit ads, but it wouldn’t be customizable or would be limited in the number of additional subreddits with certain ones that were fixed to those free accounts. The key in both cases would be to work at making Reddit still available to those third party apps via the API and not the way it was brought to those developers. Lose the third party support, lose the support of moderators who have learned to be efficient with their way of using the site, lose the site.
For a long time, before the current snafu, editing your comment before deleting it was the only way to expunge it. Probably no real guarantee, because archiving the database was already a thing, but applying the edit used to also update the archive, supposedly. If it was just delete, then it would linger after you deleted your account. Modifying your comment or post, then deleting your account, that leaves the modified comment even though you now can’t go back and make changes or delete it. The suggestion I believe is to modify the content, then just delete the account. Deleting the comment isn’t enough supposedly, because some people have said that their deleted comments have been restored.