There is at least a decent advantage in the flip phones of having the screen protected when the phone isn’t in use. I could see them potentially becoming more popular over time if they are improved upon and become cheaper, if only for that reason.
lemmy.ml isn’t explicitly “tankie” but the main devs are and the moderation will include not allowing posts/comments critical of China/Russia/communism/etc.
The title feels a bit off. I doubt very many of the subreddits have actually “relocated”. As the site itself states, these are just lists of alternatives that provide topics that match existing subreddits.
Most of the subreddits mentioned are still going to be active (especially in comparison to their alternatives) for the foreseeable future.