It is a matter of a quantum leap. European integration would be noticeably extended, and national sovereignty and self-determination would be handed over. What is crucial for this to happen is democratic legitimacy given by a clear manifestation of the will of the general public in all of the affected member states.
This is the only way to create the confidence that the new framework has popular acceptance and backing and will therefore endure. The second obstacle, which is linked to the first one, is the far-reaching amendment of the European treaties and national constitutions. This is necessary because fiscal union is not envisaged or is expressly forbidden in the existing legal framework.