The Hihiaua Precinct Plan was part of recognising the "enormous social value" in waterside areas, he said.
"These days people are starting to focus more on the beauty, lifestyle and environmental aspects of waterfronts close to city centres."
Mr Johnson had put his building up for sale but had not had a single expression of interest. He believed this was because word about the plan had got around.
"If council buy the building they will get them at a fire-sale rate ... Our building was our retirement savings, which is now worthless," he said.
The first 20/20 plan in 1996 proposed "mixed use" business and living in the area bordered by the Hatea River, Waiarohia Stream and Reyburn St. Follow-up plans reinforcing the possible changes came in 2005 and the most recent 2015 "20/20 Momentum" plan.
The land at Hihiaua was owned by WDC and the regional council, though buildings and perpetual leases were mostly privately owned.
The Johnsons said they first heard about the plan in 2006 and asked council staff where they could set up instead. They were told Pipiwai or Southend Rd were other Business 2 environments they could consider. "We have no idea how the yacht owners who spend millions in repairs year on year will get there," Mr Johnson said.
"We also provide a service to the average person - say ute owners from Dargaville who go shopping in town while they wait. Not everything in Whangarei is about selling coffee to tourists."
Graeme Smith, a manager at Stanley Marine, said if the plan went ahead the company would likely be forced to "bugger off" altogether.
"We've got nowhere else to go. We'd just shut down and walk away ... There's people moving out of Auckland and coming up this way to live. They can sell up and have a good retirement at our expense."
Councillor Phil Halse, who headed WDC's 20/20 Inner City Revitalisation Committee, said more people living in the CBD was essential to making Whangarei thrive.
The Hihiaua Precinct Plan was the pre-cursor to the District Plan Change that would facilitate development. Such plan changes followed a consultation process including public submissions and hearings.