A parliamentary committee is preparing to question the business case for the $50 billion National Broadband Network amid fears the coming rollout of a super fast 5G wireless network will make much of the system redundant.

The joint standing committee on the NBN, which last year released deeply critical findings of the network, will question whether a generation of younger city dwellers might opt out of the NBN in favour of faster, next-generation mobile services.

Committee deputy chairman Josh Wilson said fast and reliable mobile broadband threatens to “cut the lunch” of the Federal Government’s NBN network.

“It will leave parts of the NBN incapable of generating revenue, which undermines the whole business case,” Mr Wilson said said.

“It’s a nightmare scenario in which Australia gets a broadband network that is virtually obsolete at the point of delivery, and a big writedown in the value of the NBN to boot.”

The committee is expected to outline in coming weeks the terms of reference for its investigation focusing on the business case.

Associate Professor Mark Gregory of RMIT University said the NBN risked becoming the greatest white elephant in Australian history.

“I would suggest we could see 10 to 15 per cent of the nation going down the 5G path rather than committing to fixed lines,” Dr Gregory said. “The future today (for the NBN) is quite bleak.”

WA Government Chief Information Officer Giles Nunis urged caution on the idea 5G might make the NBN obsolete.

He said the 5G rollout would take a long time, and daily use would be far more expensive.

NBN Co executive manager Tony Brown said 5G networks could not deliver the data allowances given by NBN.

“At present NBN end-user premises are downloading a monthly average of close to 200GB per month compared to the average mobile download of below 10GB per month,” Mr Brown said.

Under Labor’s plan in 2007 all homes would be connected by a network of fibre optics with the monopoly company onselling access to telcos.

NBN Co collects about $43 a month per connection from telcos for use of its network, though it needs $52 a month per connection to cover costs.