2017 - Nothing is known at this time...
2018 - B&M Wing Coaster, Mack Boat Ride, New Entrance and More - (9/9/17) Toverland has begun work on the park's biggest ever expansion for 2018 and has launched a website dedicated to covering the expansion that you can see here that will include a whole new themed land, a new park entrance as well as a B&M Wing Coaster. You can sign up now to follow along with the massive new project as the news is released, though all we know for sure about the new coaster is that it will stand 131 feet tall.
(5/9/17) A great article posted to BlooLoop mentions that Toverland will undertake a huge expansion in 2018 that will greatly increase the size of the park and add two major new rides. The new rides will include a new B&M Wing Coaster and a new "boat" ride from Mack Rides that will be suitable for the entire family. The new area to house these new attractions will be behind the existing Magische Vallei.
The article also states that starting in 2018, guests arriving at the park will no longer enter through the Magic Forest building, but instead through a new outdoor entrance area that will also feature catering facilities, new shops and a performance stage.