The opening of the new Metro City has kickstarted conversations over what Sydney’s public transport network should look like in 80 years – with ­experts saying north-south links and connections to the far-flung northern beaches, southwest and southern suburbs are critical.

Next to come in existing plans for Sydney Metro will be the Sydenham to Bankstown link – due to open in late 2025 – before the Metro Western Sydney Airport line, connecting the new airport to St Marys, opens in 2026.

The Metro West, running from Westmead to the Sydney CBD is then scheduled to open in 2032, but experts argue now is the time to forge ahead with plans for new lines.

“Critical to Sydney’s long-term success is having a network of Metro rail criss-crossing across the entire city,” Committee for Sydney chief executive Eamon Waterford said. “We are growing to eight million people by 2050 … and the only way we can continue to offer people a good life, close to jobs and community, is if they’re connected by the best Metro lines in the world.”

Mr Waterford said a Metro network by 2100 should close the “loop” around Sydney – meaning linking Bankstown’s future Metro to Liverpool and Campbelltown. He added the “final piece of the puzzle” was new Metro lines from the CBD through the eastern suburbs to La Perouse, via Randwick, as well as up to the northern beaches.

Mr Waterford said “value capture” – getting developers and landowners whose property values soar in the midst of these projects to chip in to the costs of building them – should be “completely” explored.

NSW Treasurer Daniel Mookhey previously flagged he was considering the measure for the $25bn Metro West line.

Tony Shepherd, the infrastructure supremo who helmed the building of the Lane Cove and Sydney Harbour tunnels during his tenure at Transfield, said the next ­stage of the Metro “requires ease of movement around the whole city and not the typical ‘hub and spoke’ … system”.

“To achieve this we must have a future plan,” he said.

He supported a new line from Green Square to Malabar, saying it was “vital” to service the University of NSW and the densely populated Moore Park sport and entertainment precinct.

Business Sydney executive director Paul Nicolaou said the designers of the new Sydney Metro “did a John Bradfield” – referring to the visionary who planned the Sydney Harbour Bridge – by making stations suitable for the next 100 years.

He said they provided “ideal templates” for the next ­generation of stations at sites like such as Campbelltown, Camden and Sutherland.

The NSW government has already identified new areas around Metro stations like Bankstown, Crows Nest and Kellyville for thousands of new homes, with Property Council NSW executive director Katie Stevenson saying new Metro lines provided opportunity to build the homes of the future.

“We need to continue to expand our transport networks, and build more high-density, mixed-use developments,” she said. “We have an incredible opportunity to continue this visionary approach … to make smart decisions for the future of our city for the next 50 or 100 years.”