At least in the Ivy's you can in principle get a scholarship, part time work to sustain you, or gasp take out a lifetime loan, this requires a bit more thought...maybe there's kickstarter funding...hey maybe Peter N. can subsidize a deserving Hacker?
Hacker School is 4 days a week (at least this batch and last batch). You can definitely work part time during HS. I worked during the last batch of hacker school, and as a commenter above says, it's possible to live (he's doing it!) in NYC paying $650/mo in rent.
That doesn't look like an arbitrary social barrier designed to exclude the many to me. MOOCs are still there, and still awesome.
It does seem like there are probably lots of formal and informal ways of getting someone there if they've got the potential and desire. That's really good to know!
HackerSchool does give out scholarships already to some.
Also someone did run a kickstarter to get funding for their expenses in NY, and it met the funding goal almost overnight.
Hacker School is a one of a kind experience. If you attend you will be among a group of people that will have 100% participation, no one there is unsure about what they want. You also will work with some of the smartest people in the industry through the Resident program.
The Ivies give out financial aid packages far more generous than most other schools. There are all sorts of ways in which they are exclusive, but affordability (for American students, at least) is not one of them.