Chronic diseases could leave the health system in Northern Ireland facing the equivalent of a winter flu crisis year-round, an expert who recommended overhaul said.
Professor Rafael Bengoa led a review in 2016 and urged transformation of the NHS into a modern and sustainable system.
The collapse of powersharing at Stormont has affected decision-making across the public service, although a series of measures have been announced involving extra health spending.
On Tuesday Professor Bengoa said: "If we don't transform, every month will eventually start to look like January and February.
"That will not be because of the flu, but because of chronic diseases that affect older people all year round.
"Within a relatively short time, the health system will enter into crisis due to this natural demand."
In an October 2016 report - widely known as the Bengoa Report - Professor Bengoa set out a radical blueprint for transformation.
He was in Belfast to deliver a lecture at Queen's University marking the 70th anniversary of the health service and themed around reshaping care for the next 70 years.
The former Basque health minister said the system could not keep relying on hard-pressed staff to keep shoring provision up.
"They need to see that there is a willingness and determination to change, that there is hope for the future."
In 2016, based on Professor Bengoa's recommendations, former health minister Michelle O'Neill outlined a 10-year plan for improvement.
It included tackling waiting lists and boosting GP practices.
Millions of pounds have since been allocated for addressing waiting lists.
An £8.8 million investment in GP services was announced on Monday.
Professor Bengoa added: "Inevitably, demand will continue to increase sharply as people live longer lives.
"At present, too many services are based around buildings rather than being centred on what people and communities need.
"Much more care needs to be delivered in primary care settings, close to or in people's homes. That's the essence of transformation."
He said willingness and determination to change existed in abundance in Northern Ireland.
"Of course there will be frustration and setbacks along the way.
"Politics and policy making do not tend to follow a smooth path anywhere in the world.
"Transformation is a long term process."
He added: "There is still a strong consensus for change, a deepening understanding that you can't continue with the status quo."