I look at things from a very different perspective ...
At the beginning of this generation, computer hardware was at an odd point where you couldn’t build a conventional gaming console that supported advanced graphics and HD resolutions because you didn’t have the processing power available in hardware that was inexpensive enough or had low enough energy consumption/heat generation. This caused the market to go in two different directions at the same time; the HD console manufacturers bet that as people bought into HDTVs they would see the value in the HD consoles and be willing to pay more, while Nintendo bet that the slow adoption of HDTV would continue and (for most of the expected life of the Wii) HD capabilities and advanced graphics would not factor into the sales of the Wii.
In ways you could argue that both approaches taken were correct, and that both approaches taken were incorrect. Effectively, the HD console’s strategy wasn’t (particularly) effective from 2005 through 2009, while it was far more effective after that; and the Wii’s strategy from 2006 through 2009 was very effective, and after that it is seeing declining effectiveness.
Now, this doesn’t mean that Nintendo should become a third party publisher as much as it means that Nintendo should (probably) release a new system in order to switch up their strategy to become far more effective again. In doing so there is the possibility (and I would say that it is highly likely) that Nintendo could undermine the viability of the HD consoles again. The reason for this is simple, there is the opportunity to release substantially more powerful hardware with an interesting or exciting new user interface and still release the system at a very consumer friendly price.
I realize that there will be some people who say they're entirely satisfied by what the HD console's offer, but this is a common feeling at the end of the generation which disappears when people are exposed to the capabilities of new hardware.
