Which ones do you think are promising?
In my field (programming), intensive "boot camps" are very valuable and very cheap. It turns out that 90% of programming tasks really aren't that hard. A boot camp won't get you a top of the line, awesome, job, but a boot camp plus five years of real world experience where you make an effort to go above and beyond the minimum requirements will get you an education just as good as mine, at least in the programming aspect.
I've taken a lot of courses from Edx and Coursera over the last few years, and there's no way I would say that they are identical to their traditional counterparts, but some of them have been really good. Others, not so much, but none of them cost me more than 100 bucks.
For lots of fields, shorter, specialized, training programs make more sense.
For serious education, there is no way that anything is better than immersing yourself in full time study, with the aid of experts in the field, surrounded by a whole bunch of people also engaged in the same pursuit, i.e "college", but even there, there's plenty of opportunity to improve education and lower costs at the same time. The truth is that video lectures, forum based help, and expanded office hours are better than a traditional lecture and 20 students trying to get assistance in 2 hours a week of office hours. That is for introductory classes, or any classs where you could get by reading the book. Having a guy at the front of the room answering an occasional question is really not as good as having a video you can stop and play again, as well as having a forum where you can get assistance from professors, teaching assistants, and other students.
The best Edx classes were like that. I took a class that shadowed a real MIT class (Underactuated Robots, Professor Russell Teadrake), and I would say the difference between our version and their version is that we didn't have to do a final project. That, of course, is the most important part of the class......but then again there was nothing stopping me from doing the project. It just wouldn't get graded. Oh....the other difference was that my cost was a hundred bucks.
For some types of learning, computers are just better teachers. You want to learn a foreign language, get yourself a program with some exercises. For "real college" foreign language classes, do that, and meet an hour a week for pronunciation practice, and periodically take a proctored exam. You don't have to charge students 1,000 dollars for that class.
And, of course, internships and coop programs are even better in some ways than plain old college, for some lines of work.