Speaking to The Rugby Paper, Mallett said: "I think we're going to miss playing against New Zealand teams because we learn a tremendous amount from them.
"We learn how to combat superior skills and become more skilful ourselves, while the Kiwis learn that you've got to have physicality and a good set-piece.
"We've been good for each other but, going north, the quality of coaching is outstanding there, and the organisation and technical expertise of the players is very good, so we'll learn from that.
"Refereeing in the north is generally very accurate, so South African teams will have to learn quickly, and the weather up there will also play a part," he said.
Mallett said he didn't think the Covid-19 pandemic had hit the Springboks, especially, hard.
"South African rugby, just from a decision-making and skills level perspective, has always been a little bit behind Australia and New Zealand, but where we make up for it is with our power, strength and physicality.
"We have big, strong athletes who, when they put their minds to it, can mould together very quickly.
"[Lock] Eben Etzebeth, for example, can do 100m in 11.8 seconds and we produce so many of these powerful players who, when push comes to shove, can beat anyone with the physical nature of our game.
"We've also now got players of great skills in guys like Lukhanyo Am, Cheslin Kolbe and Pieter-Steph du Toit who show beautiful touches.
"Given the fact that we're never going to be short of a good pack, there's no real weakness in physicality, and that's why South Africa will always be a threat, regardless of the long layoff," he said.
Mallett said as a result of the pandemic South Africa had struggled with its rugby at the domestic level.
"The standard of rugby hasn't been at the level it should be, and there's been a strange atmosphere with no crowds," he said.
New Zealand, by comparison, had enjoyed an 'excellent' Super Rugby Aotearoa series.
"They were able to operate in a bio-secure bubble of their own and within that their rugby was very successful. I thought the Aotearoa competition produced fantastic, quality rugby. Once the referees worked out that they didn't have to blow at every single breakdown, it turned into a fantastic spectacle.
"One of the main reasons why the Currie Cup has failed to shine is because of the way the rugby laws are written at the moment, which has placed a huge responsibility on World Rugby to get it right.
"At the moment, certainly within South Africa and Europe, the team that plays without the ball generally wins the game – and surely that wasn't the point when William Webb Ellis picked up the ball. The aim was to run and pass, not bloody kick it all the time, or else he'd have carried on playing soccer," he said.