I'm still not done losing rel prev / rel next and Google's John Mueller was asked about it on a video hangout yesterday. In short, John said Google no longer uses this and no longer needs it. Google is now "able to self-detect common types of pagination setups," he said.
Google's John Mueller confirmed that the search engine continues to ignore rel previous and rel next. John said "yes they are ignored" when asked about them.
John added that Google once used them to understand pagination, but now Google is "able to detect common types of pagination setups on its own," he said. He added that Google "can process these as normal internal links and understand the context from there," adding that Google "no longer needs these special link attributes".
After Google stopped supporting these link attributes, it gave us some advice on how Google can better understand pagination on your website.
In any case, this came into the video at 35:05 in the video, here is the embedding at start time:
Forum discussion in the YouTube community.