Dunno if anything has changed since last year but this was a very interesting post by one of the authors of Cats Effect - https://www.reddit.com/r/scala/comments/sa927v/how_will_loom...

TLDR; it didn't look like it would impact effect systems much at all and most of the benefits (initially) are to make imperative code more performant. So I guess it closes the performance gap somewhat which is good, but won't be a big deal to anyone already using their own concurrency construct.