Yesterday, something interesting appeared in the ChangeLog - the first alpha of Slackware 15.0 was announced. Apparently we'll have a new major release this year. GLibC was upgraded to 2.33, which triggered a mass rebuild (of about 1550 packages). The alpha release includes updated Rust compiler, but it is not yet used by Firefox and Thunderbird, which would hopefully happen in future.
Stay tuned for more "scheduled upgrades" that would move the new release closer to beta.