Read this sentence carefully.. He KNEW she would say yes, but gave her the freedom to say no... so if HE KNEW she would say yes..could she have said no?? Could Gods foreknowledge be WRONG?
With God is not foreknowledge predestined future?
God would have come into history to offer our salvation by other means had she not said yes.
But you just said that He KNEW she would say yes..
That was speculation showing that God if He had known she would refuse He would have still acted in history to save us. Even if not by that means.