I find it challenging to even think of an answer for the question I have asked in the title. There are so many things to consider. What might the future hold that would influence the use and storage of all things written and saved today.
There is a tremendous increase in writing volume today compared to any time in our history. In the 1950's when I was a little kid I would write two or three letters a year to my friends and maybe one to my Grandma. Today I write a blog that is nearing 400 posts. If conditions had remained as 1950 I would have written very little.
Today there are thousands of blogs and the common man and woman are able to write an exponential amount because of the use of computer technology. If one browses blogs for a few minutes you can find an endless variety of well written blogs which would never have been written before this time. Some blogs are made up of endless beautiful photographs which record our life. Digital cameras and computers have made it possible for almost anybody to take photos and post them for all to see .
About 700 AD the quill pen and powdered ink was invented. A very limited amount of writing could be done. I would think that only a fraction of this writing would have survived. The common man did not write. The primitive printing press was invented about 1500. This not only allowed for more writing but more readers. The first fountain pens were developed in about 900. This allowed more people to write and more writing survived. In the 1930's the ball point was developed and refined in the 1940's so pilots could use it during the war instead of fountain pens which did not do well with great altitude changes. Even with these developments few people wrote and little was kept.
My Dad was born in 1912. I do not know of any of his writing that has survived. We did find a letter he had written to our Mom before they were married. My brother found this letter in a stove where Dad was disposing of papers. Dad had just filled the stove but had not lit a fire. I'm not sure if this letter survives.
I do not have an answer for the question I asked in the title. I can only assume that by the exponential increase in writing we will leave a vast amount of information about how we lived a this time. Archaeologists should not have to dig carefully around in the soil to find small bits of garbage to see how we lived.