NOTE: This is not a list of features that aren't implemented, this is a list of upcoming features.
Nothing much is known about Quicksilver Slimes. Not even the 7Zee Corporation and the rest of the world know about their existence. But we do know one thing about those slimes, and it's that they live in the Nimble Valley owned by Mochi Miles. They will come with Mochi's Megabucks Update (1.2.0).
Their prototype was added into the game's files in 1.1.0. The Quicksilver Slime resembles a fire slime without the flames, and it moves around faster than other slimes. It also has no largos.
The scrapped Meteor Slimes might still be added in a future update, but this is still uncertain.
At least four other slimes are said to appear in future updates. This has been confirmed from the new Plort Market and the Official Forums.
Currently none. Though it is reasonable to believe that there will be toys for each of the new slimes.
More Zone Sections/Sub Areas
Current zones will get more sections added to them and there will be more sub-areas for you to explore in the future.
More Treasure Pods
More treasure pods are planned to be added in the future updates.
Adorable Drones will be added, allowing you to automate parts of your ranching experience. Manual ranching will be still required, but drones will reduce your workload and leave you more time to explore. They will be added with Mochi's Megabucks Update (1.2.0).
This mysterious gadget might be added in a future version since it's referenced in the code. It has a good chance to be a defence against tarr.
Iron Rancher Mode
This mode adds a replayable survival-like experience to the game. It has you race against time to collect quotas of various plorts across multi-day rounds. Each round will also include mixed rules and various challenges, including vampiric chickens, random plorts, random tarr spawns, increased hunger and more. This will be added with Viktor's Experimental Update (1.3.0).
5-Day Rush 2.0
The 5-Day Rush will be revisited and improved with Mochi's Megabucks Update (1.2.0)
Viktor and Mochi will eventually offer you a daily mission as work-for-hire in new mini zones across the world. These missions will offer unique rewards as you earn favors for each rancher.
Mochi will ask you to herd the Quicksilver Slimes to corner the market with their plorts. (1.2.0)
Viktor will ask you to perform experiments in a virtual environment. (1.3.0)
It hasn't been yet confirmed whether BOb and Thora will receive a new zone.