What is the biblical foundation for considering the Bible is anything of the sort? There is nothing in the scripture contained within the Bible as we have it today that talks about the Bible. Yes, there are references about scripture in general. You seem to be referencing 2 Timothy 3:16. This particular verse does indeed seem to be explaining something about scripture in general, but it certainly isn't identifying the Bible as a volume of scripture, let alone that the Bible the end all of scripture. Again, you are simply making my earlier point about how, for some reason, many believers automatically seem to assume that scripture and Bible are interchangeable terms. If we buy into the assumption that scripture equals Bible and that Bible equals scripture, then yes, we will start to build on that assumption to interpret things much differently than had we not accepted that premise to begin with. My point is that the premise that scripture equals Bible and that Bible equals scripture is not found anywhere in the Bible as we have it today. So, in order to subscribe to such a premise, you have to go outside the Bible.
It is from the Bible, and the Bible only, we derived our doctrines and theologies. No extra writings are used.
If this is how your personal belief paradigm functions, fine. I am merely pointing out that you are presuming things about the scripture contained within the Bible as we have it today that simply can't be found within the scripture contained within the Bible as we have it today.
As far as whether it was "scriptural" to "close the books" I'm not sure. However, given there was much heretical writings flooding the market (and since I might add) the church fathers were united in this to preserve the purity of the original text. Did they make the right decision in closing the book? Given these were the church leaders who sacrifice all that they had and, in some cases, gave up their lives for the gospel and our Lord Jesus, I'd say that qualifies for a BIG Holy Spirit inspired effort.
Again, if this is how your personal belief paradigm functions, fine. However, it isn't supported by anything in the scripture contained within the Bible as we have it today. You may want to ask yourself why you feel the need to make conclusions about such and such when the Bible itself has made no attempt to do so. There are a lot of open ended issues if we view just the scripture contained within the Bible as we have it today. As such, we certainly don't need to rush to conclusions. The serious disciple, in my opinion, is more than willing to await further light and knowledge rather than rush to conclusions that certainly don't need rushing to in order to continue in one's discipleship to deny oneself, take up one's cross and follow Christ.