Could Nintendo be planning an HD version of the Wii? Despite the criticisms it has received for being under-speced compared to other consoles, such as the PS3 and the 360, it has been selling exceedingly well – with some estimates putting it at over 9 million sold already.

That said, there's considerable room for improvement – and Nintendo might be able to capitalize on it. Some analysts are expecting that a HD-capable Wii is on the way, due to customer demand. Not in the short term, but a few years down the road:

“Consumers may hope for improved graphics, and my guess is that Nintendo will comply. In two or three years, commodity prices for graphics processors and CPUs may decline to the point that a high-definition Wii could be introduced. If so, Nintendo will likely introduce one,”
The idea is intriguing. Microsoft has shown more than once that they see modifying console hardware as time goes on as a feasible and even critical part of the units success. The Wii's life may be extended significantly if they decide to upgrade future consoles, rather than completely re-engineer them.

If Nintendo ever makes official plans for such a task, it would definitely be something to look forward to.