Former prop Peter Wright, who won 21 caps for his country between 1992 and 1996, said on BBC Radio Scotland that the head coach would need to be "brutal" as he selects a squad for the Six Nations championship early next year.
He added: "Gregor has to say, 'Players X, Y and Z, thanks very much, you've been brilliant for your country but we now need to build towards France 2023 [the next World Cup] and you're not part of that'.
"I think Gregor will stay on - he'll get the Six Nations - but he will come under real pressure if Scotland have a bad tournament."
Richie Vernon, a member of the 2011 and 2015 Rugby World Cup squads, said: "From a results perspective, it's hard to argue we are going forwards.
"What's happened over the last two years is Gregor is trying to find a little more consistency to the game. They're evolving from an all-court game to a bit more of a kicking game and we're still learning how to do it.
"There are a lot of positives going forward and I do think Gregor and the coaching staff are the right people to be given more time, and find a more consistent game plan that is going to give us results long-term.
"We're just not there yet - but we've got loads of young talent coming through."
Wright agreed with Vernon, adding: "It's about wins. I'd rather play badly and win, than put the effort into technique and lose.
"The only way we're going to win away from home is to get that rugged, "dog" in to the forwards and lose our "nice guy" attitudes a little."
Speaking on BBC Radio 5 Live, former Scotland scrum-half Andy Nicol echoed fellow former international Wright's thoughts on the Six Nations, saying: "The players who were on the pitch at the end are the players that will take us to the next World Cup cycle in France 2023.
"It all comes down to the analysis and Gregor is under pressure. This now means the Six Nations becomes very, very important."
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