You should not assume that the google trend for RSS is linked to the popularity of RSS feeds. Nowadays, techies uses the term, but it is somewhat hidden for a lot of people through aggregation services and other names (atom, feed, etc.).
Contrary to the trend, there's been a handful of people moving back to decentralized sites that supports it, and a lot of big sites never stopped supporting it. And it gets advertised as an alternative, even if not under the "rss" name.