Duckett was recalled after six years for this month's tour of Pakistan and played a key role in the tourists' history-making 3-0 whitewash.
The Nottinghamshire man was the second top run-scorer in the series behind Harry Brook, making 357 at an average of 71.40 with a relentless strike rate of 95.41.
The 28-year-old was particularly adept against spin, showcasing his superb array of sweeps, but Farbrace insists he should not be pigeon-holed.
The newly appointed Sussex head coach, who worked as Trevor Bayliss' right-hand man between 2015 and 2019, was there when Duckett first tried his hand at international level with modest results but now sees a player ready for the big stage.
"A lot of people have talked about 'horses for courses', is he just a selection for the subcontinent? No, he's not," Farbrace told Sky Sports News.
"He should open the batting next summer against Australia in the Ashes, and I hope he does the same in the New Zealand series in February as well. He looks a top player and he looks like he belongs in international cricket.
"I was on the tour to India and Bangladesh (in 2016) and Ben had a really tough time, he found it difficult, but the great thing about Ben is he's gone away and worked extremely hard.
"He's worked so hard and played in a way he's probably played the way he always wanted to play."
Farbrace was full of admiration for the mindset shift that has taken place under the leadership of Ben Stokes and Brendon McCullum, but also credits their star performer of the summer - Jonny Bairstow - with making their plans a reality.
Bairstow suffered a freak leg break while playing golf in October and is set to miss the forthcoming tour of New Zealand as he continues his recovery.
But despite the outstanding success of his replacement at number five, player of the series Brook, Farbrace is certain a spot must be found for Bairstow.
"You have to have him back in the side. He was at the heart of the way England changed the way they played," he said.
"He's a sensational player. He showed when he's given that real love and support there's nobody better in your team. He's very unfortunate with the injury he suffered and he has to come back into the XI."