This Perspective has been updated.

A fundamental transformation is underway in how we access education throughout our lives. Rather than plug into the formal structures of traditional colleges and universities when we need to gain skills, a growing number of us are navigating a “shadow learning economy” from a new set of providers offering education in short spurts, either online or in face-to-face classes. Think about what we do when we don’t know how to perform an operation in Excel or need to learn a skill to get a promotion at work — we turn to YouTube or take a free online course offered by edX or Coursera.

In many ways, this behavior in education mimics that of the broader economy, with consumers increasingly seeking alternatives to legacy businesses — take Uber and Airbnb as examples of this phenomenon. In education, alternative learning providers include the likes of Launch Academy, General Assembly and Revature — hardly household names but dozens of such organizations have already attracted millions of students.

For now, these ventures operate on the periphery of higher education. Their impact on colleges and universities, if any, has probably been in graduate education, in which enrollment has been flat or declining in many professional fields as prospective students turn to these alternative providers. But a fascinating new book, “A New U: Faster + Cheaper Alternatives to College,” argues that many of these ventures are threats to expensive, and mostly second-tier, undergraduate education. And it questions “the conventional wisdom that college is the only pathway to a good first job.”

The book’s author, Ryan Craig, is a founder of University Ventures, an investment fund that backs education companies focused on helping students get training for jobs. When you first pick up the book, you might think it’s nothing more than an advertisement for some of his companies.

But Craig is unlike many of the entrepreneurs I have met working in the higher-education sphere who have little passion for its mission and bail as soon as they realize they can make more money in another industry. Craig has academia in his blood. His mother spent her career as a faculty member teaching sociology. Early in his own career, Craig was a vice president of Fathom, a short-lived online education effort operated by Columbia University that tried to sell Web-based courses and seminars to the public.

In the book, Craig argues that an “employment imperative” is driving the new learning economy and changes in higher education. In survey after survey, it’s clear that students enroll in college to get a job. The problem is — as Craig writes and I pointed out in a recent column — colleges are not delivering on this promise.

If universities “paid attention to the employment imperative, they’d be busy aligning degree programs, courses, and curricula to actual entry level positions and also significantly increasing investment in career services,” Craig writes. But career services offices are often underfunded, isolated and led by people who never worked outside of higher education. So the job of getting students a job usually falls to faculty members who are not given incentives or evaluated on that front, Craig says.

Craig writes about faculty resistance to aligning the curriculum to changes in the job market. One of the examples he cites is Bryn Mawr College, which launched an effort to infuse digital skills throughout the curriculum by soliciting advice from faculty, staff and graduates — but not employers. (Update: Bryn Mawr officials said Craig based his critique on this commentary piece they wrote in Inside Higher Ed. While it doesn’t mention employers specifically, college officials said employers were consulted).

“Can you imagine similar thinking in any other sector of the economy?” Craig asks in the book. “Does Apple let a year go by without a new iPhone release, let along five or 10? Do health-care professionals skip continuing education for years at a time?”

A college degree hasn’t been considered an admission ticket to enter a profession in the way it is today. Most people entered careers through apprenticeships, studying with a master teacher and practicing skills. One of Craig’s most compelling arguments is that the United States needs more pathways to fulfilling careers than the one that goes solely through college, and mostly four-year schools.

Indeed, one of those new pathways might be through two-year colleges. Craig writes that community colleges should shed their “academic paradigm” because most students who go to two-year schools intend to transfer to a four-year college but never do. Instead, community colleges should become what Craig calls “placement colleges” that provide short-term training to help students get their first jobs.

Higher education seen only through this lens of job training, of course, disturbs many career academics and others who argue that colleges have a much broader mission to prepare citizens for a global world and lifelong learning. While Craig focuses mostly on the career function of higher education in the book, he begins each chapter with stories from his own undergraduate experience at Yale University and what might be lost with faster and cheaper alternatives — the exploration, the serendipity and the maturation of teenagers.

Craig is not from the Peter Thiel camp of Silicon Valley technologists who advocate skipping college altogether. Early in the book, he offers a simple chart for readers to determine whether his faster and cheaper alternatives are better for them than traditional higher education. I’m more skeptical than Ryan that these ventures will become a true alternative to the bachelor’s degree, which, despite the complaints of employers, is still widely used as a sorting mechanism in the hiring process.

Even so, Craig makes a compelling argument about the second keyword in his subtitle: cheaper. College degrees have put a tremendous debt burden on recent graduates. The generation of undergraduates in college now, Generation Z, is more skeptical about taking on large amounts of debt to pay for a degree. They don’t want to turn out like their millennial counterparts. The question is whether their anxiety about debt will drive them to consider alternatives. Craig thinks the answer is a resounding yes.