Now, let's get something clear. PS4 is still beating the Switch in world wide numbers, however the only reason the Switch is selling like hotcakes is because the WiiU bombed harder than the amount dropped in Germany during WW2.
However, when the PS5 comes out in 2020. The power, the next gen games, the VR technology. It will be enough to make the Switch outdated. I expect the SwitchU to come out in 2022 after sales have died off.
Note: I did not mentioned the NextBox, because Microsoft ended up 3rd this gen, probably going to end up in 4th, behind the Stadia. Facts.