No it's implied by the fact that the states were sovereign prior to the AoC compact and had only delegated extremely limited powers to the national government, reserving most to themselves. I wouldn't get to hung up on the term "perpetual" since clearly the very same generation that used that term unanimously consented to abolishing the AoC and only rewuired 9 states of the 13 to ratify the Constitution with no intention of compelling the other non-ratifying states to join. Perpetual also means "ongoing", and not necessarily "forever". That would fly in the face of the very independent minded revolutionaries who were so mistrustful of a central government that they didn't give it the power to tax.
Oops. I misread your statement. You are correct. If ratification of the Constitution had failed, the AoC would still have been in force. I meant that if the Constitution failed and the AoC was also dissolved the states would have reverted to independence and not to a Union with an implied compact. My point is that the default, sans a contract between the states, was independence.