Actually no, the 3DS and Wii U didn't successfully coexist, in that both had good sales. The Wii U was a colossal flop. That's why Nintendo is trying this instead of just releasing a new, traditional home console.
I was saying that there are 2 separate markets and consumers: portable gamers and traditional home console gamers. Wii U flopped but the Wii did not. As I keep saying, Nintendo's console would look far more favourable imo if they positioned it first as a portable console that has the ability to also play games at home, as opposed to a home console that also happens to be a portable console. It's a small subtlety but it has a huge impact on how the console is perceived. Rumours from price, to performance all back this up.
In 2017, home console gamers will be cross shopping Xbox One S with a 4K BluRay, PS4 with its huge library of games, and for those who want cutting edge console graphics and 4K-upscaling, Xbox One Scorpio and PS4 Pro. The Switch doesn't seem competitive at all in the home console field in light of the 2017 competitive landscape. That's not even taking into account the already large libraries of Xbox One and PS4 compared to the Switch's minuscule gaming library at launch.
The Switch's specs are very disappointing for a 2017 home console (again, they are good for a portable but Nintendo is trying to cater to 2 different markets with just 1 console - imo a major flawed strategy):
The Switch is rumoured to have only 4GB of RAM.
The Switch is rumoured to have only 32GB of storage.
We also know the GPU is unlikely to be much more powerful than a 1Ghz 384 CUDA core Pascal chip, with memory bandwidth around 50-60GB/sec only. If we assume that an average Nintendo console's life-cycle is 4-5 years, the Switch would need to play next gen games from 2017-2022. As soon as PS5/XB2 launch in 2019-2020, it's going to be extremely hard to port 3rd party games to such weak specs. That's why the Switch's launch timing is not optimal either.
We are also getting rumours that the Switch's base console SKU may cost
$249 USD/£199.99. Once again, this is good for a portable console with a bonus feature to connect to a TV but clearly this isn't even mid-end home console hardware.
By all accounts, this should not be marketed as a direct competitor to Xbox One/PS4 and their 4K counter-parts. And this is perfectly OK but only if Nintendo doesn't try to sell us the marketing BS that the Switch is also Nintendo's next gen home console from 2017-2022. They will not be able to get the traditional home console gamers back who simply wanted the next SNES/N64/GameCube style console.
What about the price of games? Currently, most AAA games sell for $59.99 USD or $79.99 Canadian. I don't think it's reasonable to charge these prices for what is essentially a portable console. I think that's why Nintendo is so desperate to try to market the Switch as a home console since they want to make up the low cost of the console with much higher game prices. Right now 3DS games sell for
$39.99 USD or
$49.99 Canadian. I am not sold on the idea of an underpowered 2017 home console's games costing $60 USD/$80 Canadian because then I am going to be comparing the total experience to the PS4 Pro/XB Scorpio and the PC.
That is why I think Nintendo should have a $249 Switch and then a $399-449 home console but it seems they aren't going to have it this generation. Maybe I am wrong, but in my eyes, they are abandoning the traditional home console market. A large portion of console gamers simply do not care for mobile gaming. Once we hook up the Switch to a TV, it becomes just another underpowered Nintendo console, exactly just like the Wii and Wii U were. Just like the Wii and Wii U, it also comes with compromised/weird controllers, thus forcing gamers to spend extra $ on the Pro Controller. Just like the Wii and Wii U, the console is gimped with low storage again, forcing the gamers to get external SD cards. For someone who will buy the Switch solely as a home console, the $249 price sounds more like a marketing gimmick since it'll cost another $70-80 to get the Pro Controller and a 128GB SD card. (And how exactly is Nintendo going to fit next gen AAA titles on an SD card when games are already approaching and exceeding 100GB? It won't be cheap with SD storage).
Once the early adopter sales and the initial hype dies down, and we approach 2019/2020 when many expect XB2 and PS5, the Switch risks becoming irrelevant in the home console market. That doesn't mean it won't sell well, but those sales will likely be coming from the same gamers who wanted or bought portables such as the 3DS and Vita, etc.