I don't think that's true in the slightest. not only would Nintendo decrease their fan-base's confidence in their ability to support a console for a reasonable amount of time, they'd probably decrease the confidence in the potential markets that they would try and appeal to. if Nintendo cuts support for the Wii U after 3 years it wouldn't send the best signal to prospective owners of their next console.
The general populace essentially doesn't care about the Wii U. They don't care it exists. They don't care how long it exists. I highly doubt it enters into their mind frame.
If it does, I don't particularly know why extending the stench of failed product on the market with perpetual software drought is supposed to be particularly inspiring for future purpose.
It certainly won't inspire confidence in retail and publishing partners.
Who are the prospective owners? What do
they care about?
That's what should be running through Nintendo's executives' minds.
They should be working on a product towards appealing to those broader markets, as quickly as possible, and launching it when it make sense for
that product.
Not simply ensuring the continued support of the last remnants of their most ardent fanbase by protracting its lifespan. Because again, if that's the extent of the market they're catering to, then it's an exercise in futility. You keep those few million people on board again next time around in 2018 after a "full" console cycle? Okay. So you have Wii U take two then.