At any point last season, even when Vettel's relationship with Charles Leclerc reached its nadir with their collision during the Brazilian Grand Prix, to suggest the possibility of the four-time champion switching to the Silver Arrows at some point seemed laughable.
Even during pre-season testing, there was no hint from team principal Mattia Binotto, nor Vettel himself, that within the space of a few months under lockdown there would be a parting of the ways.
With Valtteri Bottas out of contract (again!) at the end of the year due to the rolling nature of his agreement with Mercedes, there is a seat available for Vettel.
It throws up the mouthwatering probability of Hamilton and Vettel, the two most successful drivers of the modern era, and who have won 10 of the last 12 world titles between them, going head to head in the same team.
After all, Vettel pretty much ticks all the boxes when it comes to the criteria Wolff and Mercedes attach to driver selection.
In a recent video interview for the team, Wolff outlined what is required.
“You look at race results, back into the junior formulas, you look at comparisons with team-mates and how these team-mates compared to other people, and then there is the personality side, which is very important," said Wolff.
“How would the driver fit into the team structure? What would the dynamic be with the driver who could be his team-mate? What’s the planning for the future?"
And then there have been the numerous mistakes during races that have undermined his championship challenge in recent years. That would certainly a cause for alarm.
In terms of personality, Vettel is one of the more personable, and at times outspoken characters in the paddock; he has the interests of the sport at heart, as underlined by his directorial position on the GPDA; and, as a father of three, he also has family values.
As Wolff recently stated, he has "a friendly relationship" with Vettel, which would naturally be of importance to any boss if he is to move his team forward, so it is fairly evident he would fit into Mercedes' structure.
The key question for Wolff to answer is with regard to the dynamic between Hamilton and Vettel.
There has been rancour in the past, with the relationship between the two hitting rock-bottom when Vettel - in a moment of madness - deliberately turned his Ferrari into Hamilton's Mercedes during a safety car period in the 2017 Azerbaijan Grand Prix. The fallout that followed was epic.
Those cracks have since been plastered over, and it is obvious there is now considerable respect between the duo.
But how would Hamilton feel in having Vettel as his team-mate, something that would undoubtedly alter the dynamic between the duo, as witnessed between the 35-year-old Briton and Nico Rosberg?
"In 2013, it was still pretty much easy-going because we weren't fighting for race wins, and we used to be best friends, so that was a decent start," reflected Rosberg.
"But then going into 2014, that's where you noticed because once you are fighting for race wins and championships, there is so much at stake. Your dream is at stake.
"Both of us dreamed of winning the world championship with Mercedes. It's so big. It's hard to make compromises, and it's the friendship that gets compromised, in return for winning races."
A Hamilton/Vettel partnership would surely deteriorate the same way.
There is no doubt Hamilton has been comfortable the past three years with Valtteri Bottas by his side. Whilst the Finn has improved during that time, he has still failed to consistently challenge.
You get the feeling that whatever season transpires this year, it will be Bottas' last opportunity to prove he has what it takes to be a world champion. He has had three attempts so far in cars that have carried Hamilton to his drivers' titles and the team to its constructors' championships, and he has yet to get close.
While Hamilton has never been afraid of a challenge, and in many respects would welcome Vettel as a team-mate, conversely, you expect he would likely prefer his final years - if this is to be his last deal - to be quieter than the animosity he endured alongside Rosberg.
Wolff is also aware of the George Russell conundrum, a young driver with immense talent currently with an under-performing Williams team and deserving of so much better, even if he is likely learning an untold amount that will stand him in good stead for the future.
When you consider former Mercedes juniors in Esteban Ocon, Pascal Wehrlein and Nyck de Vries have all moved on due to the fact they were unable to get their chance with the team, surely Wolff is unwilling to pass over another potential star in Russell.
Of course, we would all love to see Hamilton and Vettel fight it out on track in equal machinery - an older guard if you will against the young guns in Max Verstappen, Leclerc, Norris, Sainz and Ocon.
But it is hard to picture such a scenario for exactly that reason. Two 'veterans' in the team does not make sense for Mercedes. There has to be a degree of succession planning, and that will surely be top of Wolff's agenda when he muses over his driver line-up from next season.
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