Goldsworthy & the New Covenant

Alicia and I are reading through Graeme Goldsworthy's "Gospel and Kingdom." I really appreciate Goldsworthy's writing ministry and recommend everything he has written for a better understanding of the unity of Scripture and its message to the church. However, the other night, I had to pause our reading to sermonize on the importance of developing a biblical theology that is rooted in the text. Goldsworthy is right on, for the most part, but on pg 101 he writes,
"There is in fact an essential unity to all the covenants. Jeremiah shows the unity between the Mosaic covenant and the new covenant (chapter 31:31-34), for the new covenant is not a new thing replacing the old, but rather the old renewed and applied in such a way that it will be perfectly kept."
I certainly agree that there is an essential unity to all the covenants. They are an essential unfolding to the one plan of God (Eph 1.10), but Jeremiah does not show the unity of the Mosaic covenant and the new. Quite the opposite. Jeremiah says, "I will make a new covenant with the house of Israel and the house of Judah, not like the covenant that I made with their fathers on the day when I took them by the hand to bring them out of the land of Egypt, my covenant that they broke" (31.31-32). I am not sure how much clearer Jeremiah could have been. God is going to make a new covenant, not like the old one. It will be new, not renewed, or a new administration of the old! There is radical discontinuity between the old and new covenants. The new covenant is an eschatological covenant that fulfils all the other covenants. Within this covenant, all will know the Lord and have the Spirit, unlike Israel of old, who for the most part was apostate. Significantly, when Hebrews quotes the long Jeremiah text (8.8-12), he immediately says, "In speaking of a new covenant, he makes the first one obsolete. And what is becoming obsolete and growing old is ready to vanish away" (Heb 8.13).
Of course Goldsworthy (and other Covenant Theologians) don't like the idea of a new new covenant because of its implications. If there is discontinuity with the new covenant and all within it know the Lord and have the Spirit, that means that by definition the new covenant community (the church) is a believing community! That means that only a Baptist ecclesiology is faithful to Scripture, and hence, infant baptism must be abandoned. But the Westminster Confession won't allow that, will it?