The South Korea international moved to the Stadium of Light on loan last summer after being deemed surplus to requirements by Michael Laudrup at Swansea.
He has played an important role in the Black Cats' revival under Gus Poyet, helping them out of the Premier League drop zone and through to the Capital One Cup final.
Sunderland are eager to wrap up a permanent agreement, with Poyet saying: "We definitely want him to stay."
Ki, however, admits he is in the dark as to where he will end up.
He said in the Daily star: "I don't know if I will be playing here next season. I've no idea what will happen in the future, but right now I am happy playing for Sunderland.
"Since Gus Poyet came in, we have improved with and without the ball and are a lot more confident.
"Reaching Wembley and winning the derby were special and I am pleased with how things are going."