Nintendo's Shinya Takahashi was at the BAFTA Games Awards 2018 to represent Nintendo and their nominated games. At the event, Mr. Takahashi had a brief interview with the BBC. Surprisingly, Takahashi let loose with this tidbit about future Nintendo hardware.
Nintendo constantly works on hardware, so we have been doing research and development. So you may see the new system sometime in the future.
I honestly don't know what to make of the statement. It comes out of nowhere, especially when you consider that Takahashi gave this statement as an answer to the question, "Do you think the success of the Switch has come as a surprise?" I mean, his response doesn't make any sense!