The cloud delivery and consumption model has revolutionized the entire IT industry over the past decade, as evidenced by the dramatic rise of public cloud services, according to IDC.

But the research group adds that cloud opportunity extends well beyond the public cloud — which makes up less than half of all cloud-related spending today — and includes private and hybrid clouds, as well as managed cloud services, cloud-related professional services, and hardware and software infrastructure for building clouds. In its first forecast of the "whole cloud" opportunity, IDC estimates that worldwide whole cloud revenues will reach $554 billion in 2021, more than double those of 2016.

"The most obvious takeaway from this forecast is that the shift to the cloud consumption model – in all its forms – is a mass movement, and will continue to be such over the forecast period," said Frank Gens, senior vice president and chief analyst at IDC. "Equally important, though, is the steady drumbeat of tech innovation that is coming from the major public cloud suppliers, making it virtually impossible for enterprises and developers seeking advantage through IT not to embrace the public cloud.”

The past few years have produced a steady stream of innovative new services introduced by the major public cloud service providers, including blockchain services, IoT back-end data services, encryption services, serverless computing services, and even new computing hardware services. IDC expects the pace of innovation on public clouds to continue and, more likely, to accelerate.

Similarly, IDC expects to see a steady expansion of enterprise workloads on the cloud as cloud service providers and their partners focus on new deployment scenarios for these workloads. Despite lingering concerns about security, vendor and technology lock-in, and interoperability, IDC believes that cloud computing will continue to dominate and transform enterprise computing for years to come. Key highlights from the new forecast include the following:

° Public cloud wins. In 2016, public cloud services accounted for 41% of all cloud-related spending. By 2021, this figure will increase to 48%. And, when spending on hardware and software that enables public cloud services, and managed and professional services around the cloud are included, these figures rise to 65% and 68%, respectively.

°Services supporting public and hybrid cloud environments are hot. Spending on managed and professional services around cloud adoption are, collectively, the second largest opportunity in the whole cloud market, accounting for 31% of all cloud-related spending in 2016 and 2021.

° Infrastructure for cloud services providers dominates. The hyperscale datacenters operated by cloud service providers are dramatically altering the market for infrastructure hardware and software. By 2021, cloud service providers will account for 76% of cloud-related infrastructure hardware and software spending.