Fitzpatrick said the improving Scots could make a big impact at the global showpiece.
They were only denied a place in the semi-finals of the 2015 event when beaten in a controversial finish in their 35-34 loss to Australia.
In Japan in 2019, Scotland will play Ireland and the winner of that game in Pool A is likely to avoid a quarter-final against the All Blacks, who are in a group with South Africa and Italy.
"We're talking mid-cycle now in terms of the players they're developing and they've got a real core base of players now – they've had a lot of injuries this year – but in doing that they've developed a lot of other players that wouldn't have had that opportunity," Fitzpatrick told the BBC.
Scotland fielded a number of players Fitzpatrick hadn't heard of before in their win over Scotland and he thought that was wonderful.
He said they had played well against the All Blacks when losing 22-17 a week earlier.
"People will say how well Scotland played – and they played very well – but the All Blacks played well too, to win," added Fitzpatrick.
"Scotland did play the game of their lives and the pleasing thing for me, if I was a Scotland fan, was the way they backed that up seven days later when they played Australia.
"Most teams play well against the All Blacks and then drop their performance; Gregor Townsend has done a great job and built on a base that Vern Cotter has developed over the years.
"He's now giving them free licence to get out there and play rugby. Pleasing in the last two weeks I suppose is that they scored tries but they also defended very well."
As a result of what he had seen in the November internationals, Fitzpatrick thought the Six Nations next year would be more competitive than usual.
"Having England at home will be an advantage to Scotland, I suspect," he said.
"You could say that Ireland, England and Scotland, then we get Wales… it's going to be one heck of a Six Nations.
Then you throw in the French and we don't know who's going to turn up. Italy will be challenging, also."