Everytime I see this graph I am thinking that Switch is doing very poorly in Japan especially since it is supposed to replace both the handheld and the console.
Is that the consensus? Or what is the general view of Switch performance in Japan?
It's hard to get a consensus because people have different barometers of success.
From a financial point of view it is hard to argue that the Switch is doing poorly, just check the yearly earnings. The combined sales of the WiiU and 3DS were a LOT higher than the Switch alone but Nintendo is making more money now.
From a "number of systems actually in households" it gets a bit more tricky.
The graph you quoted shows (launch aligned) the 5 highest selling consoles in recent history. If we add contemporary systems like the PS4, Vita, Xbox 1, PS3, 360 to the graph you would see that the Switch, time aligned, is significantly higher in sales. [can we get such a graph?] But what that means will depend on the reader.
Most important is the readers definitions of poor and good. If for example, someone thinks the PS4 is doing "good" then the Switch, which is selling more units launch aligned, is doing "better than good". If someone thinks the Switch is doing "very poor" they would also need to agree that the PS4 (in Japan) is doing "worse than very poor".
If the break even point for "success" is unit sales (not revenue) equaling PS2, DS, 3DS, Super Famicom, etc. then yes, the Switch is doing very poor.
That's why there is so much discussion in media create threads. We all have the same numbers, but varying expectations, viewpoints and bias.
I hope that helps.
EDIT: While I was writing this I see Hiska-kun put up a graph that connects to one of the things I was saying. Cheers.