Interesting question to ponder. You have to ask yourself essentially, would the soccer moms and other people of the expanded audience have bought a Wii for games like Wii Sports/Wii fit/ Wii Play/ NSMB/ Mario Kart Wii at $599? Some bought the Wii at $250 just to buy Wii Fit, which costed another $100. Some bought a Wii on ebay for over the market value just to get one at or near launch. I sold an extra Wii I bought to a mother at $350, who told me how grateful she was to get one for her son for christmas.
The games will always be the main selling point of a console, while price is secondary. If a console has good enough games that people want badly enough, then price won't be much of a factor for people. So the answer is yes, I think a good part of the Wii audience would still have bought the console, because it still has the same compelling games that these people would have wanted just as much. Would it have sold less? Probably, but probably not as much as some people think.
Same deal with the Xbox 360, although I think the value ofthat console is tied more to the price, because it is very similar to the PS3 and competing directly against it. I know I decided on 360 over the PS3 because it launched $200 cheaper than it, and I haven't looked back since. So the 360 sales probably would have suffered more. But basically, I think the sales would be more equal than they exist now, but the standings would still be the same: Wii>>>>>360>PS3