Sarri has reportedly been granted a release by Premier League side Chelsea so he can replace Massimiliano Allegri on a three-year deal in Turin.
Allegri guided Juve to five successive Serie A titles before parting ways with the Italian giant at the end of 2018-2019 and Pjanic has no concerns about the club's future.
"We are not worried at all, Juventus will be strong as always," Pjanic said.
"I'm really happy to play against Italy in Turin. I think my red card against Greece was not fair, fortunately they removed my ban because I wanted to play against Italy in my stadium so badly.
"I repeat, I'm not worried about Juventus. They'll announce the new manager soon. As everyone is saying, our new manager will be a great one, for sure."
Juve's Allianz Stadium will be the location for the qualifier between Italy and Bosnia, who will be boosted by the return of Pjanic.
Pjanic was sent off in Bosnia's 2-2 draw at home to Greece in March, having given the host a 2-0 lead.
Italy tops Group J with three wins from as many games, five points clear of third-placed Bosnia.
"It was not simple [for Italy] to come back. It was possible thanks to the experience of [head coach Roberto] Mancini but also to the leaders of this group," Pjanic said.
"Great professional that helped a lot even the young players after a bad moment for the national team. It's very unusual a World Cup without Italy. They are playing great football, people like watching them playing. It wasn't easy. We know that they are the favourite of the group, we'll try to stop them. It will be a difficult match because they have lot of great players."