The way things are going, I'm confident Nintendo is going to earn back a lot of lost market share this generation. It's still a bit too early to say just how good third party support is, we keep hearing great rumours, but only time will tell how that pans out. It's also too early to tell if the non-gamer approach will work very well.
In spite of those things, there's so much interest in the system from the hardcore community, I suspect it will easily outsell GameCube, and probably more or less match N64 sales, at worst. It could conceivably take off and outsell any console previously released if Nintendo actually captures the non-gamer crowd. Even without non-gamers, Nintendo could still take first place if there's enough third party support and enough games that make it more fun to play than a traditional system.
Unfortunately, squeezing out competition by underselling them is nothing new, and I don't think it's illegal or anything either. Just nasty. In fact, one of the companies that formed IBM decades ago was the National Cash Register Company. They were known for undercutting competition to force them out of business, and then making a profit by charging high prices for maintenance on the cash registers. Some of the tactics they used may have been illegal, but overall I don't think it's something you can do much about. It would likely cost more to fight this type of business on the legal battlefield than it's worth.