"I think if Brodie and Julian decided post Rugby World Cup to move on then it would be really bad news for us," says Sorensen.
"You would have to start saying we are not doing something right here and you would have to say it was a trend. It would have been great to keep Charles [Piutau] and Colin [Slade] - but you wouldn't want to lose two more current All Blacks.
"We can confidently say they are world-class players but they have also got a lot of rugby ahead of them, too. I get that a player might play here in New Zealand until they are 28, 29 and then have the rest of his career offshore. I can respect that and empathise with that.
"What we don't want to do is have a whole bunch of our top 40 players disappear when they are 22, 23-year-olds. If Julian and Brodie decide they are gone as well it will be a major issue for us."
Both Retallick and Savea are expected to reveal in the next two weeks whether they have signed to stay in New Zealand until 2017 and their decisions are being viewed as the most significant since Richie McCaw and Daniel Carter had to determine in 2008 whether they were willing to play through to the 2011 World Cup.
With a number of senior All Blacks - Carter, Ma'a Nonu, Conrad Smith - having confirmed they are heading offshore and others such as McCaw, Keven Mealamu and possibly Tony Woodcock likely to retire, the national side is already facing a major rebuilding job in 2016.
There is the added pressure of some players such as Sonny Bill Williams and Liam Messam having signalled they would like to try to play Sevens at the Olympics which will remove them from the first five tests of next year.
Retallick, the reigning World Rugby Player of the year, and Savea, arguably the world's most devastating wing, who was short-listed for the same award in 2014, could potentially plunge the game into crisis if they move on.
The All Blacks need them both next year. They are the new McCaw and Carter - the two men who elevate the All Blacks to a different level.
But not only do New Zealand Rugby executives fear the immediate playing impact of either leaving, they are also concerned it will signal a new era - one where the best players in the country are no longer willing to give their best years to the All Blacks.
Retallick and Savea have intimated they are leaning towards staying, but Piutau and to a lesser extent Slade were as well until they respectively signed with Ulster and Pau.
Piutau has been offered a deal worth about $1 million a season while Slade's contract is believed to be around $700,000.
Even these huge figures are thought to be well below the money top European and Japanese clubs would pay for Retallick and Savea.
Putting a market value on either is difficult but it is believed both would fetch in excess of 1 million ($1.4 million) a season in Europe.
What's giving NZ Rugby a degree of confidence, however, is the lack of speculation elsewhere.
Typically word leaks out from offshore as they close in on big name players.
It is also believed that NZR has offered both Retallick and Savea salary packages that reflect the overseas demand for them.
"We have a lot of dialogue with them and their agents," say Sorensen. "Brodie is in massive demand offshore and he's also a young man, newly married, who is looking at his options which is a good thing I think.
"We don't want them to stay in New Zealand because they have to, we want them to stay in New Zealand because they want to."
