According to a leaked document, Samsung plans to update select models in the mid-range of to Android 4.4 KitKat. Models alleged to see the update include the Galaxy S4 Mini, Galaxy S3 Mini, Galaxy Ace 3, Galaxy S Advance, Galaxy Ace 2, Galaxy Core, Galaxy Fame and Galaxy Fresh.
Google’s “Project Svelte” optimizes Android 4.4 to be compatible with devices that have as little as 512MB of RAM. Ideally, this means low-end devices will have the opportunity to update to KitKat as well.
Note that these are for specific model numbers and that timelines are not listed. We should hope that Samsung makes some formal announcements for these, and variations in the near term. Assuming the list is accurate, of course.