Because Samsung hasn't run out of letters in the Latin alphabet, it's getting ready to launch the Galaxy C on May 26 (that's next Thursday). The event will take place in China, so expect a China-only launch.
So far we've seen two devices leak - the Galaxy C5 and the Galaxy C7. They will come with 1080p screens (5.2" and 5.5" respectively) Android 6.0 Marshmallow and a generous 4GB of RAM, a Snapdragon 617 chipset (C5) or its replacement, the Snapdragon 625 (C7).
Going by these specs, the new Galaxy C series will be above the E and J, but below the A and S series.