While Sony Corp. (SNE) remains mum on initial sales of PlayStation 3, a Nintendo Co. Ltd. executive says the company’s on track to meet a goal of selling 4 million Wii consoles globally by the end of the year. The risk is not geared to demand, but to its ability to manufacture enough units.

Wall Street had already expected Sony and Microsoft Corp. (MSFT) to easily sell their new-generation consoles and for manufacturing to be the issue that determines whether they meet, miss, or beat their expectations.

What’s new is the fact that Wii’s initially strong reception. For some early, anecdotal evidence, we find an aggregate 4.5 star rating from 165 Amazon.com customer-reviewers, versus PlayStation 3 with 4 stars from 72 customers and Xbox360, with 3.5 stars from 469 customers. If that sort of trend surfaces in other places, this has the potential to change the next-generation gaming competition from the two-horse race many expected to a three-horse race.

It’s also possible that Wii may expand the market by attracting new gamers, something it expressly set out to do with its less-tech-intensive design philosophy and its new motion-sensitive controller. It’s not clear right now to what extent, if any, this is factored into the price of retailer GameStop (GME) shares. Analysts have been focusing mainly on the impact of hardware availability. The possibility that Nintendo may expand the market is something that, if it materializes, would likely be visible around, or possibly after, mid-year.

Analysts have 7 Buy ratings, 5 Outperform ratings and 3 Hold ratings on GameStop stock, for an average of 1.73 on a scale of 1.00 (best) to 5.00 (worst).