Ron Vlaar has revealed he could yet sign a new deal with Aston Villa this summer.
Liverpool have declined to comment on reports midfielder Jordan Henderson has signed a new five-year deal at the club.
The Germany international, who came through Manchester United's youth ranks before joining the Bundesliga side, is understood to have a clause in his contract which allows him to leave if a big club comes in with an offer.
That clause may also extend to any club should Hannover fail to qualify for Europe, Kind told Germany's Sky Sport News on Wednesday.
"If we don't reach our goals, then it cannot be ruled out that he suddenly activates a clause in his contract," Kind said.
Hannover missed out on a place in Europe this season after back-to-back campaigns in the Europa League.
After 10 games of the season, they are currently lying 10th in the table, although only two points separate them from a place in the Europa League, which is Zieler's minimum aim.
"I'd like to be playing in Europe and it's important to see how Hannover develop," said the 24-year-old, who is tied to the Reds until 2015.