The public cloud market has taken a few years to take hold, but enterprises are starting to bite, and there’s more upside than you might have expected.

In a new report today, Forrester forecasted that the public cloud market will reach $191 billion by 2020 — a figure almost 20 percent higher than a $160 billion estimate the analyst firm made three years ago.

“While the last several years can best be characterized as exploratory for most enterprises, cloud services and cloud platforms are now an undeniable part of the IT landscape,” Forrester infrastructure analyst James Staten wrote in a blog post on the report.

Basically, Staten wrote, the world has begun its shift to the second stage of cloud adoption. Or you could call it a hypergrowth phase. In recent months others have suggested the trend is playing out, and now a big analyst firm is confirming it.

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But Forrester’s analysts aren’t naive. They know big companies have their share of concerns about running their applications on infrastructure they don’t own: the security of data in other companies’ hands, for instance, as well as the ease of integration to existing on-site services. Security remains the biggest hurdle for cloud adoption, according to the report.

Even so, the expectations of growth bode well for cloud companies.

Cloud-based software — known as software as a service, or SaaS — continue to represent the largest share of the cloud market. Last year the SaaS market came in at $52 billion, and by 2020 that number will come out to $133 billion, Forrester said.

But impact of the cloud market’s expansion surely will also extend to the infrastructure as a service (IaaS) providers. Amazon Web Services, the IaaS market leader, should be in for good times in the years to come. Fast-rising ones like Microsoft Azure, Google Compute Engine, and smaller but increasingly visible DigitalOcean are likely to enjoy the benefits of a bigger public cloud market in general.

Enabling technologies like Docker and analytics tools like Cloudability and Cloudyn could enjoy perks, too.

Besides the vendor impact, applications could become faster for companies big and small, and schools, and governments, and individuals, to cook up and scale and drop. That’s part of the public cloud’s promise. But instead of wholesale replacement, companies are complementing their existing IT with public cloud services. Products that complement, not replace, are in a better position to grow at this point, according to the report.

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