This question strikes me as being a bit silly.
Of course, if somehow, every Bible on the face of the earth were destroyed, God could communicate directly with His creation.
In fact, I think we've all heard of conversions that have happened in recent times, without any Bible. I was particularly struck by the story of a young Chinese mother who was out cutting grass...she gathered it and dried it to sell...and she had her little baby with her. They were attacked by a hungry animal. The woman had met a missionary, but all she understood was "Jesus saves." So, she cried out for this Jesus to save her...and the hungry critter was distracted by an injured critter who became his lunch. He left the mother and baby alone. I read that story in a book entitled "Jesus Freaks" by D.C. Talk that tells all sorts of stories like this.
But these things are the exception, rather than the rule.
The Bible is God's chosen method for communicating with His people today.
The men who wrote it were inspired by God. Now, if God thought it was important enough to inspire these men to write, and the writers took the time to do the work...the least we can do is read the thing.
Most of us would never have heard of the God of the Bible...without the Bible.
Is the Bible necessary for salvation? I can't say that it definitely is, in every case.
But, in the majority of cases, it is definitely instrumental...