I don't know what these guys are thinking, it is like they are impervious to facts. As annoying as Pachter is sometimes, he seems to be pretty spot on with Nintendo and I totally agree with him.
Nintendo's day 1 profit business model plus their war chest accumulated from the DS/Wii has given them a lot of room for error with the Wii-U. Even if it is only a niche console a la Gamecube, it still won't cause them to sink. They can always reboot in 4 years and try again. Losing relevance is a definite risk, but things move so fast these days and people have little loyalty to brands. If you have the special product like the Wii was, irrelevance is a small hurdle.
I still think it is ridiculously early to be jumping onto the "Nintendoom" bandwagon. The console has been out 3.5 months and there hasn't been a major 1st party release this year. If things don't pick up during the next holiday period, likely after a price cut and major 1st party titles like Kart and 3D Mario, and possibly a more robust Wii Sports, then sure, Nintendo needs to start planning their next console in earnest and really evaluate who their audience is going to be for that console, something I'm not sure they did with the Wii-U.
That said, I am enjoying mine. I will be buying plenty of games for it this year.