I'm happy with retiring Tumbleweed and Reversal badges.
Especially I like how Reversal badge was treated. It wasn't just retired: it was replaced by Lifejacket and Lifeboat badges, utilizing the positive effect of Winter Bash, encouraging people to search for hidden gems in questions, improve them and this not only for 2 weeks.
Unfortunately, much more frequent Tumbleweed badge wasn't treated so good. It was just retired without positive replacement and encouraging any effort from users to answer these unheeded questions. I'm sure getting a good answer would encourage users to stay here much more than receiving nothing.
Also, we had this kind of hat at Winter Bash 2016 to encourage answering questions with Tumbleweed badge:
Answer a question qualifying for the Tumbleweed badge. The answer must get accepted and reach a positive score.
So can this "Lifesaver" badge be added? We can name it "Lifebelt". I'm sure this bronze sibling would be useful for Lifejacket and Lifeboat family.
I'm trying to suggest a way to encourage people to focus on answering abandoned questions. Existing Revival and Necromancer badges encourage answering just old questions and it's more profitable (from point of getting these badges) to answer popular questions rather than abandoned ones.