Ronaldo’s exit from the Allianz Stadium after three years was officially confirmed on transfer deadline day.
Juventus moved quickly to re-sign Kean on a two-year loan deal with an obligation to buy from Everton.
Kean started his career at Juventus but joined Everton in the summer of 2019. The 21-year-old’s spell on the blue half of Merseyside proved unsuccessful but he enjoyed a loan stint last season at Paris Saint Germain where he struck 17 goals in 41 appearances across all competitions playing alongside Icardi.
By contrast, Icardi made 28 appearances and scored 13 goals last season for PSG.
"Before Ronaldo left, I had said that Juventus' attack is stronger,” Vieri told La Gazzetta dello Sport.
"Juve were stronger. Now, I put Inter in front. Cristiano's 25 to 30 goals are gone, those who said it wasn't going well will be happy. When Ronaldo leaves, there are no better options.
"But someone else must score the goals he scored. I don't think Kean will be able to get that many, but I think it's right to give him a whole championship to judge him.
"Icardi is someone who plays little for the team, but he's a finisher by trade, it's easy for him to score 20 goals. Since there's a need for those 20 goals, maybe I would have done more to get him.
"But in the market, it's not always possible to do what seems best."