It turns out, that the Switch checks all these boxes. If you design a screen for a 3DS successor with is slightly larger and higher res, you arrive at the screen of the switch. It is also the same size as the screen of the WiiU. And docked, it outperforms the WiiU as stationary console. Of course it falls behind the PS4, but I think the market for non-portable consoles has been "won" by the PS4. But while they will continue to exist, the prime time for stationary consoles might be over too. With the Switch, you are no longer tied to the TV. Nintendo took quite some care to make sure that the Switch mostly performs identically docked and undocked. There shouldn't be many if any games which are tied to one mode only.
The popularity of gaming laptops should tell us, that there is an increasing number of people who want to be mobile in their gaming, not necessarily as in playing while riding the bus, but as in taking your gaming hardware with you when like visiting friends. And that is, where the Switch easily outshines for example a PS4. Add to it the ability to do multiplayer gaming on the local network (Splatoon2, Mario Cart,...) and it has a lot of prospect.