The Linux Mint team published several important items in their October newsletter. One of the bigger changes mentioned is the KDE edition of Linux Mint will be discontinued after the release of Linux Mint 18.3. The KDE Plasma desktop has a different ecosystem and toolkit which make it quite a different envrionment when compared next to the other Mint desktop editions and the team has decided to focus on the Cinnamon, MATE and Xfce editions. The Plasma desktop will still be available in the distribution's software repositories for people who wish to install it.
The newsletter also reports the third version of Linux Mint Debian Edition will be released in the first quarter of 2018. The new version will be based on Debian 9 "Stretch" and be available in just one edition featuring the Cinnamon desktop. In addition, the Mint team is working on bringing Flatpak universal package support to the distribution: "Linux Mint 18.3 will ship with Flatpak installed and configured by default to point to two Flatpak repositories, called 'remotes': Flathub and Gnome-apps. A new section was added to the Software Manager for Flatpaks. Although Flathub and Gnome-apps are configured by default, you can modify the list of remotes. If you add new ones, they will appear in the Software Manager. Packages and Flatpaks are completely different things, but in the Software Manager, they're presented the same way: They're just applications you install."