Don't know what the author is talking about.

Assembly, Summer 2023: https://assembly.galleria.fi/kuvat/Assembly+Summer+2023/Perj...

Assembly, Summer 2024: https://assembly.galleria.fi/kuvat/ASSEMBLY+SUMMER+2024/PERJ...

Looks like plenty of attendance, lots of elementary through high school age attendees. Lots of families bringing their children. Site's got 1000's of pictures of evidence.

Maybe the scene has change in a way they don't especially want to attend over the years, yet it does not seem to be "dying". This post on LinkedIn claims Summer 2023 had 25,000 attendees. Seems healthy.

https://www.linkedin.com/posts/lassinummi_assembly-summer-20...

Minor edit: Also, still have all the results and competitions each year. Demo, 1k Intro, 4k Intro, Short Film, Dance Music, Freestyle Graphics, ect...

Results, Summer 2023: https://assembly.org/en/events/summer23/posts/assembly-summe...

Results, Summer 2024: https://assembly.org/en/articles/assembly-summer-2024-compet...