Milne said the real question was whether NZ's long standing and well-justified image as a safe place to travel would be eroded by the terror attacks.
"Tourists were not the target and this appears to be very much a 'one-off' attack.
"The global coverage post-attack is very much showing a nation that is embracing the role of love and forgiveness in overcoming this immediate challenge.
"One could argue that this casts NZ in a positive light."
Last year, Christchurch hosted more than 558,000 visitors - both domestic and international - who spent $2.3 billion in the city.
Local police advised the city was safe, but foreign embassies would likely be advising visitors to be vigilant.
"I remain sceptical that the impact will be significant," Milne said.
"We need to look at any downturn in the context of broader economic and political forces that are already having an impact on projections of future visitor numbers."
The Ministry of Business, Innovation and Employment also today confirmed that the China-NZ Year of Tourism launch event in Wellington will go ahead as planned on Saturday, despite telling the Herald last week that it was "under discussion".
Although supportive of the event, Milne said it would have been better for a delay.
"It makes sense to proceed but perhaps to delay given the current circumstance is not a bad idea.
"I think it is a respectful approach."
A separate China-NZ Year of Tourism event at the Cordis Hotel in Auckland hosted by the China Consulate has been cancelled.
In an email, vice-consul Ankai Chen said the event had to be called off "due to the current situation and circumstances".
A number of events were local events were cancelled in the wake of the shootings, including the annual Pasifika Festival last weekend.
But Auckland Council events manager David Burt said the Auckland International Cultural Festival scheduled for Sunday, April 7, at the Mt Roskill War Memorial Park will carry on as planned.
"We think it's important to recognise and acknowledge our cultural differences and come together as one.
"The festival reflects contemporary Auckland and we want people to enjoy each other's company through music, dance, food and a touch of sport too."
Rana Judge, the organiser of the Diversity Festival which celebrates the diverse cultures and communities of South Auckland, confirmed that the festival would also be going ahead at Hayman Park in Manukau on Saturday, April 6.