Omicron and a lack of data are the latest culprits cited for uncertainty over major travel decisions.
On the same day a petition to overhaul MIQ was presented at Parliament, ministers said Kiwis will have to recognise the Covid-19 pandemic keeps changing.
"With reporting coming in, Omicron is likely to become the dominant variant in London in the next 48 hours," Prime Minister Jacinda Ardern said today.
"I think Kiwis understand why we move carefully."
New Zealand citizens and residents returning from Australia will be allowed to bypass MIQ from January 17.
Ardern said key travel dates will be reviewed at a meeting just over a week before then.
The latest information on Omicron will be assessed on about January 7 or 8 and adjustments made if necessary, Ardern said.
"If we roll forward self-isolation when Omicron is dominant in Australia, it will effectively be the start of Omicron here."
The PM said the severity of any variant, and the impact of existing vaccines would be assessed.
Asked if fully vaccinated Kiwis from anywhere overseas could return and not have to isolate next year, Tourism Minister Stuart Nash said he'd like to think so, but could not say for sure.
"You look at what's happening in Europe at the moment. There's another wave of Covid going through, there are governments reintroducing restrictions."
He said it might be months before relevant data was available to support some decisions around travel and tourism.
"There are numerous variables that we will need to consider before we relax managed isolation.
"Once we understand what is happening in our communities, once we get a lot more data, then we can make decisions."
On domestic tourism, Nash said he recognised the pain the industry had been going through.
Northland will stay in the red traffic light setting when everywhere else moves to or stays at orange just before the New Year.
But Nash said vaccinated people could still enjoy the region's attractions.
"If you're planning to go to Northland, I wouldn't cancel those plans. You can't have a large concert up there...but if you're fully vaccinated, go to Northland."
"My advice to people is, think carefully before you travel," Covid-19 Response Minister Chris Hipkins said when asked about Kiwis planning to visit Australia.
"When we opened the transtasman bubble we did so on the basis of flyer beware, and any changes in the New Year are also on that basis."
Hipkins said any issues with people getting stuck overseas would have to be dealt with at the time.
"In terms of the international border, the issue really is Omicron and understanding the new variant, and understanding what the consequences of that are."
He added: "We've got a variety of different plans, but people do need to be conscious that the global pandemic is not over."
Grounded Kiwis, a network battling what it calls an inhumane and frequently absurd MIQ system, presented a petition at Parliament today.
Anthea Black was there to support her daughter-in-law Claire Doherty. They stood among a small group in the drizzle outside Parliament after driving from Levin.
Black was there as the petition of Alexandra Birt was presented. The petition had 22,888 signatures.
Claire's husband Andrew has been stuck in Australia and his loved ones say the MIQ booking system is inhumane.
Black said she felt bad for other people whose relatives had tried without luck to get home. Her son will fly home soon, but only after months of trying.
"He tried and tried and tried to get home and he couldn't get through the system. There are lots of people in dreadful situations."
Black said it seemed crazy for fully vaccinated New Zealanders to still have to jostle for MIQ spots.
MPs from Act, National and the Greens were there for the petition. Birt addressed MPs by Zoom, appearing on a tablet screen.
"This petition is about a fundamental right...the right of citizens to return to Aotearoa, our turangawaewae," Birt said.
She told National Party immigration spokeswoman Erica Stanford she'd only got an MIQ spot on her 7th attempt.
"We have a perversion of priorities in the country," National's Covid-19 response spokesman Chris Bishop said.
He said people with the virus were allowed to isolate at home but fully-vaccinated people without Covid-19 were bundled into MIQ.
"It is cruelty and it is callousness."
Dr Elizabeth Kerekere of the Green Party said, "Anybody who has made their life here, and committed to this country, from wherever they've come, or from however many generations they've been living here, they have a right to come home."
Act leader David Seymour said, "We've had an abundance of caution in our Covid response. Where is the abundance of kindness for these people?
"2022 must be the year that people who have worked so hard for justice actually get it, and we see a humane response and a risk-proportionate response to this pandemic."