The so-called gig economy will cease to exist in 20 years, according to a new report from venture-backed start-up Thumbtack, an online marketplace that helps skilled workers find customers. The study predicts that logistics companies — from start-ups like Uber to tech giants like Amazon — will soon replace drivers and delivery workers with autonomous vehicles and drones. Highly skilled workers, such as lawyers and accountants — no longer guaranteed jobs at big firms — will be the new gig economy workers, the study finds.

A UberX driver calls a customer she is picking up, in Washington, DC. Evelyn Hockstein | The Washington Post | Getty Images

"The gig economy as we know it will not last," Jon Lieber, chief economist at Thumbtack, and Lucas Puente, an economic analyst at the firm, said in the report. "In the past few years, analysts and reporters have obsessively focused on transportation technology platforms such as Uber and Lyft and delivery technology platforms such as Instacart and the workers needed for these on-demand services. This narrow focus on low-skilled 'gigs' misses a larger story. These relatively commoditized, undifferentiated services are supplementing income, not generating middle-class lifestyles. Moreover, these tasks are overwhelmingly likely to be automated over time, performed by self-driving cars and drones."

Uber is upfront about its plans to replace drivers with robots over time. "Autonomous driving technology has the potential to drastically reduce deaths in cars and make transportation even more affordable," an Uber spokesperson told CNBC. "That's an exciting future and one Uber intends to be part of, but that transition for technical, regulatory and adoption reasons, at scale, will take some time." "In the meantime, our focus is providing flexible work opportunities for as many people in the world as possible," said the spokesperson.

Almost half of U.S. jobs are at high risk of computerization over the next 20 years, according to Oxford academics Carl Benedikt Frey and Michael A. Osborne. Their findings were published in 2013 and remain unchanged, though there are some caveats — such as resistance from stakeholders and relative wage levels — that will determine if a job is in fact automated, said Osborne. Predictions about how many jobs robots will ultimately displace vary widely. "We forecast that 16 percent of jobs will disappear due to automation technologies between now and 2025, but that jobs equivalent to 9 percent of today's jobs will be created," said Forrester analyst J.P. Gownder in a report. "Physical robots require repair and maintenance professionals — one of several job categories that will grow up around a more automated world." Taking a global view, more than 3 million workers will be supervised by a "robo-boss" by 2018, research and advisory firm Gartner predicted late last year.

The jobs least likely to be automated first are those that require a high level of creativity or emotional intelligence, Osborne said. For example, school teacher jobs are relatively safe because of the elevated level of social intelligence required to teach and mentor children. Positions that are particularly vulnerable to automation include telemarketers, tax preparers, watch repairers, insurance underwriters, cargo and freight agents, and mathematical technicians, the Oxford study found. Within each category, some jobs will be automated sooner. "There are a lot of driving tasks today that really only require the navigation of relatively structured environments," said Osborne, co-director of the Oxford Martin Program on Technology and Employment. "In those types of environments, autonomous vehicles are very much on the near horizon."

Driving jobs on mining sites are already being automated and long-distance truck drivers, forklift operators and agricultural drivers could be replaced within five to 10 years, he said. Professional drivers navigating complex inner-city environments, tricky intersections and pedestrians crossing roads involve all the higher-end difficulties of driving. That's why Uber drivers will be the last to be replaced by robots, perhaps within a couple of decades, said Osborne. In the meantime, the gig economy is creating invaluable data to feed Uber's algorithms and build artificial intelligence systems — the brains of those robots. For example, an Uber driver is sending back a lot of data on where customers are as well as traffic and road conditions.