The season starts in the Austrian resort of Soelden this weekend with men's and women's giant slaloms on the Rettenbach glacier.
Shiffrin has 88 career wins after breaking Ingemar Stenmark's long-standing record 86 last season, when she also took 14 victories over the course of the year.
The American also took 17 wins in 2019, her most dominant season, and 12 in 2018.
"My theory would be that she’ll have a dominant season," Miller, a two-times World Cup overall champion and the most successful American male skier of all time, told Reuters in a telephone interview from Soelden.
"She’s proven time and again that she has the class to do it," he added of the possibility of Shiffrin winning 12 races or more to reach the century.
"She continually overcomes the obstacles, overcomes challenges and continues to perform. Any time we are talking superlatives, she’s the best there’s ever been."
Miller, in Austria for the European launch of his Peak Ski Company's recreational skis, said it was not like Shiffrin was some flash in the pan.
"She’s done it since the beginning of her career and she’s expanding into all the different disciplines with incredible class," he added.
"If she comes out and has that kind of look she had at times last year, then yes I think she could do it. She certainly has the consistency to do it."
Shiffrin told Reuters this week that she wanted to see how much faster she could ski, how much further she could go in the sport.
She will focus more on downhills, the most dangerous discipline of all.
Miller, who won 33 World Cup races in all five disciplines, said that carried risks but Shiffrin was different.
"She’s so stable and so strong and she just so rarely gets out of balance that I don’t see it as the same type of risk that I would have said for a lot of the men I saw transition from the tech side," he explained.
"She is surely exceptional and we’re witnessing the best there’s ever been. That’s something to be excited about."
ODERMATT AGAIN
On the men's side, Switzerland's Marco Odermatt finished last season with a record points haul and Miller agreed it was again hard to see other than more of the same, although the margins of error were small.
He also felt Odermatt had it slightly easier than might have been the case in the past.
"Not to knock the World Cup field, but I don’t think it’s as deep as it has been 15 or 20 years ago where we had really deep World Cup fields and 15 or 20 guys could win and they all had their formula," he said.
Miller said Peak could eventually build race skis, for juniors as early as this winter, but felt there was little to be gained commercially with recreational skis now so different.
The six times Olympic medallist also recognised the sport would have to change in the face of global warming.
"For me, low on the priority scale is whether or not we can have World Cup races. That’s a luxury," he said. "What’s more concerning is the storm systems... That’s much more of a real issue, where we’re talking of human lives and likelihood of mass migrations.
"I don’t think skiing’s going to go away. They’ll have to make some changes. We’re facing the reality that things are changing and we can’t continue the status quo."
