Many people suggest that it is all the new technologies that are generating an upheaval in the work of IT departments and therefore of CIOs - cloud computing, mobile devices, social media, big data and the like.
But this is only a partial truth, and one that misses the main point.
In my view the prime force that is driving the present revolution is not the new technology but the new consumer.
Millions of consumers of all ages (not just the young, as sometimes suggested) are now accustomed to getting all the services and all the information they want, any time, any place, quickly and easily.
They are also used to instant communication and plenty of it, and increasingly unwilling to tolerate those who can't play by the same rules.
Initially the impacts of this driving force are at their greatest in B2C areas such as retailing and consumer communications, as evidenced by the rise of Amazon, Apple, Google and the like.
But they are also carrying through increasingly to the rest of the economy, B2B as much as B2C, and public as much as private sector – and for obvious reasons.
People accustomed to instant results in their private lives won't want to do business with – or work for - organisations unable to function to the same high standards.
Seeing the consumer as the driving force also highlights the fact that the changes predicted are coming from the outside in, not fundamentally as a result of internal initiatives.
In some companies individual departments like marketing have been responding to these changes faster than IT, spending considerable sums from their own budgets, outside the CIO's ambit, for example on rent-an-app cloud applications or IT tools for social media analysis.
Nonetheless a controlled response to the 'outside in' forces of change surely demands that the CIO remains at the centre of new IT initiatives.
And this poses three challenges for CIOs – their architecture, their operational processes, and their portfolio of vendor contracts, all of which are at risk of becoming endangered species as the digital revolution intensifies.
Current IT architectures generally present major interfacing challenges in accommodating new cloud-based services or mobile applications or social media.
Current operational practices depend upon IT staff with deep knowledge of specific architectures, in contrast to the broad knowledge of a much wider range of techniques, technologies and applications that is now required.
And current commercial arrangements, based on an assumption of stability over several years, need to be re-thought in the fast-moving new world.