Linux Mint developers while announcing Linux Mint 17.3 release, revealed some information regarding Linux Mint 18. They reveled that, Linux Mint 18 will be featuring Cinnamon 3, upcoming release of Cinnamon. They also hinted that Linux Mint 18 may come with a code name Sarah.
From a news article published in softpedia
The Linux Mint developers have just revealed that the 17.3 branch of the operating system will be called Rosa and that it will land sometime in the next few months, but they've also said some other interesting stuff regarding the upcoming 18.0 version.Continue Reading
Developers usually think ahead of the next release, and they are usually preparing for the future versions ahead of time. The fact that we hear about some new features or ideas at the proper time is just about timing.