One of the things I find interesting is that it won't necessarily be tied just to popos. I believe other distros are looking into it. (Can't find references now)

If anyone is interested in the 'why', here's an old (1 year ago) thread [0] explaining why they are moving away from GTK.

[0]: https://www.reddit.com/r/pop_os/comments/xs87ed/is_iced_repl...