Regarding the market for this plane, yes there is a market. If you travel frequently in/around Asia, you'll know that there is a market, let alone the trans-atlantic and trans-pacific.
But, the money that's made on this plane is not to cramp more seats in there on these flights. Yes there will be more economy seats than a 747 currently have, but most of the spaces will be configured for first class and business class traveling, where the real money is made.
I fly quite often, lets say more than 100K miles a year, and sometimes, it's hard to find an open seat in first or business to upgrade (if I purchase tickets at moments notice) on international flights. If you think that there are not enough people flying, you obviously haven't been to an airport lately. Funny that I noticed there are more emptied seats on domestic flights than there are on international.
Give them sometimes, the world only produce more people, which mean they'll succeed.
Edit: Sorry, have to put my two bits in regarding South West. They're profitable not because they fly the small airplanes, but their business model is most efficient. They fly the SAME model on all routes, so that means they can fly any model and still be profitable. That translates to crew familiarization to the same airplane, less trainings (both on operation and maintenance) since they only have to worry about one type of airplane, etc...