The consultancy IDC is predicting that IT professionals will spend more than $72.9 billion on cloud services by 2015, and that technology advancements in cloud will radically transform IT environments for the next 25 years.

The firm further forecasts that the IT landscape will be altered by how cloud services connect with advancements in mobile devices and networks, data and social networking, calling the integration of those sectors with the “third major platform for long-term growth” following the mainframe and PC eras.

The IDC study defines public IT cloud services as those offerings commercially offered to a largely unrestricted marketplace of potential users, and the forecast does not include revenue from private cloud deployments dedicated to a specific customer. However, IDC says its expectation is that public clouds will mature and eventually incorporate many of the capabilities—including security and availability—that distinguish private clouds today.

Additional findings from the IDC study include:

•    In 2015, public cloud services will account for 46 percent of net new growth in overall IT spending in five product areas: applications, application development and deployment, systems infrastructure software, basic storage and servers.

•    Software-as-a-service will account for roughly three quarters of all spending on public cloud IT services throughout the forecast—incorporating not just applications, but also spending on servers and storage associated with SaaS providers building out their infrastructure.

•    The United States will dominate overall spending throughout the forecast period, with nearly 50 percent of all public IT cloud services revenues coming from the U.S. in 2015. IDC expects regions outside the U.S. to show stronger growth as cloud services adoption accelerates, particularly in Asia/Pacific and Western Europe.