Virgil van Dijk, Trent Alexander-Arnold and Mohamed Salah all have contracts due to expire in June.
Ahead of Saturday's clash with Brighton, Slot was asked about the trio: "The contract situation could become an issue if the players don't perform as they do at the moment, but they are so mature.
"At the moment all three of them are in a good place and there are ongoing discussions, like Virgil has said. They are not with me, we talk about other things.
"Let's wait and see but all that he says is completely right. He doesn't know exactly what the future holds if he doesn't sign the contract."
On the situations of left-backs Kostas Tsimikas and Andrew Robertson, Slot also said: "I wouldn't it's say a dilemma. There are other positions where we have rotated.
"It probably also has to do with Robbo's pre-season. He had no pre-season because he came back injured from the Euros so he missed almost the whole pre-season. For most of them it was only two weeks but for him it was only a few days.
"Kostas did really well in that period of time so it has to do with the quality Kostas has in that position but it also has to do with Robbo missing pre-season. That's why we started rotating from the start a bit. That's the situation.
"It was good for Robbo to play against Arsenal and against Brighton in midweek. That is making sure he is getting into that rhythm of playing twice a week."