The Nintendo Wii and DS obviously won't last forever -- certainly not in their current forms. Nintendo president Satoru Iwata admitted as much in an investor call (via Eurogamer), saying that Nintendo is "always researching and working on new hardware" so they can "be launched whenever we find a very interesting idea."
"You may not be able to believe this, but even when Nintendo has completed a hardware, it does not mean that we will surely launch it," he said.

"[New] hardware is not needed until the time our software developers see the end in making new software with the existing hardware, or unless we have no more new market to explore and all the potential consumers have purchased our hardware."

Iwata also commented on a potential price cut, saying, "I have never said that cutting the suggested retail price is not in the cards."

However, "Accordingly, if we really do enact a price cut, it must be exactly when it can maximize the business. At least for now, I have no specific ideas about the price cut at all."