Williams brings a linebreaking and offloading portfolio that will give the All Blacks greater threat closer to the set-piece and ruck as well as enabling them to continue with their wide game.
For that reason, he'll most likely be returned to the starting XV as early as the second Bledisloe Cup test in Wellington - if he's deemed to be in good enough physical and mental shape after Rio.
That doesn't prevent Ryan Crotty from being considered one of the other certainties, as he delivered precisely what he was asked to in three tests and provides a stability and accuracy that has genuine value in test football.
The probabilities are Ngatai being cleared to play shortly and making a smooth transition back to rugby with the Chiefs and securing a spot in the Rugby Championship.
His ability play both 12 and 13 is important and with Malakai Fekitoa able to do the same, those two will be locked into the 32-man squad when it is named in August. The hard-to-tell is George Moala, who greatly impressed with his direct and bullish aproach in Dunedin, but came off with what is a moderately troubling arm injury.
"His elbow is pretty sore, what he's done is stretch the ligaments around the joint so he could be [out for] three or four weeks,"confirmed All Blacks coach Steve Hansen.
"He certainly got our interest last night. Sonny is going to come back after the Olympics and Charlie has to come back and we have some other people who have done a good job for us so we will have to make some decisions."
The most likely solution to the overcrowding is that Moala, should he recover, will be retained and out will drop both Seta Tamanivalu and Damian McKenzie.
The ability of Beauden Barrett to cover fullback allows that scenario to play out without being unduly concerned at the lack of options in the back three.
The revival of Israel Dagg and continued excellence of Ben Smith are two of the bigger positives to come out of the series and for much of the Championship, the decision each test could simply be whether to start Julian Savea or Waisake Naholo on the left wing.
The respective contributions of the two throughout the series would lead many to see Naholo as the favourite but Savea probably has the inside running.
"I just want to see him enjoy himself and enjoy his rugby and get his confidence back,"said Hansen on what he wants from Savea in the next phase of Super Rugby.
"Slowly it is coming back and he is not to far away. He got away to an horrific start last night thanks to Izzy [Israel Dagg] getting in his way, but he bounced back and he didn't get much come his way and he certainly didn't get a lot of room to run.
"Once he starts scoring tries again I think we will see the smile on his face. I think he is in good shape to go back to Super Rugby: his weight is the best it's been, he's quick so physically he's in good shape he just has to get his confidence."
Choose your own midfield
All Blacks selectors have a plenty of options to fill their midfield in the opening game of the Rugby Championship:
Ryan Crotty
Malakai Fekitoa
Sonny Bill Williams
Charlie Ngatai
George Moala
Seta Tamanivalu
Ben Smith
