I don't think you are using the phrase "it is possible" correctly. There's certainly no evidence that a philosophical zombie is "possible". I think there are strong arguments that it's not possible.

Well, I could have been clearer, but it was a proposition, hence the "If this is true" in the following sentence.

That being said, I don't think those counter arguments really invalidate the philosophical zombie thought experiment. Let's say that it is not possible to simulate a conscious being with 100% accuracy. Does the difference really matter? Does a living organism need consciousness as an evolutionary advantage?

Isn't it reasonable to assume that all human beings are conscious just because they all pass the Turing test, even if they are not?