What If New Scriptures Were To Be Found?

I've often wondered what the church of Christ would do if some archeological dig found a forgotten lost book of the Bible. Oh, I know there have been many so-called "Lost Books of the Bible", but I'm talking about the genuine thing.

For example, Paul writes to the Colossians in Col 4:16:

After this letter has been read to you, see that it is also read in the church of the Laodiceans and that you in turn read the letter from Laodicea.

Here we have a God-inspired account of the existence of a letter written by Paul to the Laodiceans, apparently carrying equal weight as the letter to the Colossians as regards inspiration, which we do not have today. What if that letter were to show up, here, nearly 2000 years later? How would it be received?