In the words of injured Chiefs loose forward Luke Jacobson, the All Blacks is "not a team where your place is just there – you have to earn your way in", and McKenzie finds himself in the position of needing to do just that.
Jordan has had a breakout year in the No15 jersey for the Crusaders, leading the competition in just about every attacking statistic and making a massive impact every time he touches the ball.
Since returning from injury, Barrett has been a difference-maker for the Hurricanes through his long-distance goal kicking, playmaking and his ability in the open field. Of course, the selectors don't pick solely on form. However, being at the start of a World Cup cycle, it should be a big factor in such a hotly contested position.
But while Jordan and Barrett have outperformed McKenzie during the season, the North vs South match provides different opportunities.
While Invercargill-born McKenzie appears the clear choice at the back for the North, having made his provincial debut for Waikato, Jordan and Barrett are in direct competition for time at the back for the South.
Barrett is in a case similar to McKenzie's. Growing up and doing his high school years in Taranaki, he made his provincial debut for Canterbury. It's the same case for one of his brothers, Scott, while Beauden remains North-eligible after debuting for Taranaki.
As the All Blacks march into a new era on the road to the 2023 Rugby World Cup, the North vs South match is the culmination of the first chance for players to put themselves in the mind of national selectors.
While 2020 has been a strange year due to the Covid-19 pandemic, the first year of a World Cup cycle gives teams the opportunity to bring in new players, or begin to blood them for higher honours closer to the big dance. McKenzie (25), Barrett (23) and Jordan (22) are all going to be around in 2023 and, barring severe injury, will still be up to performing at the highest possible level.
And while Jordan has been the standout fullback in Super Rugby Aotearoa, either he or Barrett is likely to find themselves on the right wing for the exhibition match, with Crusaders youngster Leicester Fainga'anuku the only other feasible option; Sevu Reece, Caleb Clarke, Rieko Ioane and Mark Telea are all North-eligible. There's also a chance five-match All Blacks David Havili gets the fullback duties – in summary, it's a logjam at the back for the South.
There is more to the wider equation in the form of Beauden Barrett. A two-time World Player of the Year who has spent plenty of time in the No10 jersey for the All Blacks in recent years was used at fullback in 2019, with Richie Mo'unga at first five-eighth.
Mo'unga has been one of the best players in Super Rugby Aotearoa and it's hard to see him taking a back seat to Barrett. But does that mean Barrett stays at fullback, or does he move back to a bench role in which he can utilise his running game against tired defences late in the piece?
However, that's a question for later. For now, the question is around which young fullback will make their mark, and given the depth in the position, it's something to excite Kiwi rugby fans across the country.