Looking at the competition nobody is even close to the "fraction of the cost" unless we are talking 9/10 or 4/5 as fractions.
You can get a lighter and much more powerful Lenovo or Dell laptop but not for what you would normally call a fraction.
And despite their good build quality, neither the masses nor the Mac complainers are buying XPS's or X1's. The reason is of course that they are neither universally better not significantly cheaper.
Apple is still by far the best at things that are hard to put on a spec sheet, while Lenovo and Dells spec sheets are kicking Apples ass.
And you are not going to see things change or a new player come in and take this market, because the market for laptops is shrinking. This is why apple is trying to increase revenue per unit and unit churn rate. Us premium laptop users are becoming a niche.