The main theme of the new covenant with Christ is that it supersedes the old covenant and its promises. The new covenant is a new and better covenant that is based on the blood of Christ, rather than the blood of animals (Hebrews 8:6-13, 9:11-14).
In this sense, the new covenant with Christ does indeed negate the previous promises, at least in the sense that they are no longer the primary focus of God's relationship with humanity. The new covenant is a new and better way of relating to God, one that is based on faith in Christ rather than obedience to the law.
The flaws I mentioned earlier are more related to the interpretation of the Old Testament promises, rather than the main theme of the new covenant with Christ. However, if we accept that the new covenant with Christ supersedes the old covenant and its promises, then it's possible to argue that the previous promises are no longer relevant or applicable.
In this sense, the new covenant with Christ can be seen as a fulfillment of the Old Testament promises, but also a transcendence of them. The new covenant is a new and better way of relating to God, one that is based on faith in Christ rather than obedience to the law.
It's worth noting that the apostle Paul writes that the old covenant is "obsolete" and "will soon disappear" (Hebrews 8:13), and that the new covenant is a "better covenant" that is based on "better promises" (Hebrews 8:6). This suggests that the new covenant with Christ is indeed a new and better way of relating to God, one that supersedes the old covenant and its promises.
In this sense, the main theme of the new covenant with Christ can be seen as a fulfillment of the Old Testament promises, but also a transcendence of them. The new covenant is a new and better way of relating to God, one that is based on faith in Christ rather than obedience to the law.