I consider the discussion on-topic, since we’re talking about what and why happened and how to avoid such issues in future.
I also am reasonably sure that the unvisited structures get deleted, as it was officially announced in this forum post Coming HWS meta change on 09.09.2016 - 9AM (GMT+2) | 3AM (EDT)!
and no official announcement was made since then.
Not sure what you mean by that.