I found these articles and an interesting video on “Is OLAP Dead”…hint, no it isn’t. It will never die!
These are a little old (from Oct 2017), but they have a lot of good summary information.
OLAP: Past, Present…and Future? – This is an article that covers a little history and chats about OLAP as a technology past its prime.
Is OLAP Dead (article) – This is an article that talks about where OLAP is at the time of the article.
Is OLAP Dead (video) – This is a webinar covering a summary of OLAP concepts and technologies.