I have no idea if Switch will be a success or failure. I believe in it, it feels like the hype is real, and Nintendo seem confident.. At the same time I really liked Wii U as well, loved the potential of the two screens, but overestimated developers ability and desire to be creative. I honestly don't believe the online system was the problem. If the momentum from Mario Kart 8 had been kept, if NSMBU/SM3DW hadn't been perceived as Wii/3DS ports, if Super Mario Maker and Minecraft had been there sooner, if the HD Zeldas didn't come to market as apologies for delaying the main game, if they had SW partners with a wider appeal than "fan favourite" Platinum. It's not each "if
" individually, but the sum of them all.
At launch we can see that the 3rd party issue still is there. EA does not seem to believe. FIFA18 for Switch looks like even more of an insult than FIFA13 for Wii U was. I'd be surprised if Ultimate Team is part of it. They will fail at the FPS genre. Car racing has never had a place with Nintendo. Any online competitive game unless it's their own IP is doubtful at best.
Again, the hype might be real, but when the "if"s start adding up, then we're back to the same thing that's been the problem with every single Nintendo console since the N64 (including Wii, which was a phenomenon for other reasons), that you just don't know if or when a 3rd party multiplatform game will show up. Even with GameCube, where they had the hardware to be competitive, it was still a lottery if a game was PS2/XB/GCN or just PS2/XB.
As a console owner, and never knowing if you need another console to play a certain game, it's the biggest problem Nintendo have, and I don't see Switch as the solution. It might become wildly successful for other reasons (like Wii), but the 3rd party software problem remains as the cancer they cannot find the cure for.