The five players will leave for London on Sunday. The first job for Mo'unga, who spent last week in Brisbane as cover for Barrett, and Drummond (and Bird) will be to attempt to win another national provincial title for Canterbury in their premiership final against Tasman in Christchurch the day before.
It would be unfair to suggest first-five Mo'unga, who is yet to play a test, has gained on Lima Sopoaga following the latter's performance for the All Blacks in the defeat to the Wallabies in Brisbane. But there is no doubt Hansen's men missed the pace and defence-splitting running ability of the injured Beauden Barrett at Suncorp Stadium.
At his best, Sopoaga can also be an explosive and elusive runner, but there was little evidence of that on Saturday night. Also, it was his poor pass which was intercepted by Reece Hodge for the Wallabies' first try and he turned the ball over several other times.
Sopoaga had a brilliant debut against the Boks back in 2015 and should bounce back from this, but it highlighted how far ahead Barrett is. One of the Hurricanes player's greatest gifts is his pace and that can create opportunities out of nothing for the All Blacks, who often looked disjointed and sluggish on attack in Brisbane.
Mo'unga's ability to get in behind the defence for the Crusaders with his step and pace was a major reason why their offence worked so well on their march to the title.
For Drummond, the opportunity at Twickenham and behind next month is probably even greater. Mo'unga has Barrett, Sopoaga and probably Damian McKenzie in front of him.
With Tawera Kerr-Barlow heading to La Rochelle in France after the November tour, Drummond is in the perfect position to push for the All Blacks' third halfback spot behind Aaron Smith and TJ Perenara.
The gap between Smith, Perenara, Kerr-Barlow has been too large for the All Blacks selectors to talk about other halfbacks in the mix but now Drummond has a chance to stake his claim.
For Mo'unga and Drummond, who with their three other New Zealand Barbarian teammates will assemble with the All Blacks for the French leg of the tour (a test against France in Paris on November 11 and a France XV in Lyon three days later), the opportunity is real - long lunches or not.