Thirty years ago, infrastructure was mostly a public arena. Over time, the line between public and private services has blurred (as we've noted in previous years' trends). In some cases, this is exactly what governments wanted. Many have been working hard to create and sustain public-private partnership models across a wide variety of sectors.

In other cases, the shift has been unexpected. New subscription models for everything from power through to public transit (think Uber); the digitization and commercialization of services (think healthcare); and the rise of new technologies (think hyperloop) are all bringing new competition into traditionally monopolistic markets and generating new opportunities for governments to create and use spare capacity.

For most governments, this is a good thing. Public budgets and capacity are stretched thin. Few, if any, governments are able to deliver an infrastructure agenda on their own, and most view private participation as a smart way to improve service, increase consumer choice and reduce costs.

The problem is that private players are, for the most part, interested in earning a commercial return and judge their actions and investments primarily against this criterion. Governments, on the other hand, must look across a bigger canvas - such as wider economic benefits, better resilience and positive social and environmental impact. Shifting delivery and ownership to the private sector may alleviate the resource pressure, but it does not remove governments' wider responsibilities.

The reality is that, should any of the private models fail, it will be governments that are left to fix the problem. What happens, for example, if private power producers fail to meet public energy demands? Or if privately-run hospitals go bankrupt? Or even if digital disrupters go offline? Who will citizens expect to fill the gap? Invariably, the answer is government.

This year, we expect to see governments start to ask some tough questions about how they plan to fulfil their basic role in an increasingly privatized infrastructure environment. What level of `baseline' services should the government maintain in reserve to offset the risk of failure? And at what cost? Regulators, in particular, will need to take a lead role in driving these discussions and encouraging negotiations across multiple infrastructure sectors.

This, in turn, will lead to some difficult (and potentially politically sensitive) decisions. Some governments, for example, will decide to forge ahead with massive nuclear generation projects - recognizing that the economics are challenging - in order to assure a consistent and reliable supply of power. Others may continue to run bus services (even on unused routes) in order to keep a basic level of capacity available.

Ultimately, governments will need to consider how they create an appropriate balance between encouraging private participation while ensuring public service delivery. New models may need to be created; new or different investments might be made. These are tough choices that need to be debated openly and transparently, because no government can afford to wait for a failure.