I haven't heard of this "new ACM format", but for years I've wished for a PDF2 that incorporated lessons learned from PDF and web pages for print, ebooks, web on multiple screen sizes, and non-visual readers (for the blind but also for anyone who would like to "read" a book or paper while driving or jogging).

A "multi-view" format that could be viewed as full page layout (both scrolling and paged), small screen linear, audio-only linear, or machine-readable (full, deterministic text sequence, tabular data, alt-text and tags for images and charts, etc.) All pages, images, fonts, etc., would remain encapsulated within a single file.

The closest I've seen is the latest ebook format, but that doesn't have anything close to the power of PDF to lay out a proper textbook or magazine article page.

Isn't that just HTML?

Markdown comes to mind