A Bloomberg report contained a small snippet of detail regarding this, with sources stating as such. They’ve also confirmed that the slight upgrade to the Switch, on the other hand, is said to arrive by this year, with no exact time frame.
The report also states that the slight upgrade to the Switch is the only more powerful version of it being worked on. Other rumours about a sequel to Nintendo’s current console appears to be untrue, with the same sources close to Bloomberg stating that such a thing is not in the works. Also mentioned in the report is the fact that the Pokémon franchise is officially moving to the Switch from the 3DS. Other franchises will also be making their way to the Nintendo handheld console, such as Animal Crossing and Luigi’s Mansion. (Source: Bloomberg via My Nintendo News)