"Long ago I learned from your statutes that you established them to last forever." (Ps 119:152)
The scriptures need not bow to our rules of logic (which are perfectly miserable and unable to increase one cubit of our stature). We may learn from the bible itself that the bible was established by God to last forever. There is no higher authority to which we can appeal in our understanding of scripture than scripture itself. It is Christ's own word.