Obsolescense

I keep worrying about obsolescence issues that threaten to deprive us of what we have today. Think of all the data that we are amassing from pictures, to videos to word documents to excel spreadsheets to pdf files. What will happen to all this data decades from now if the jpg compression format would no longer be there, or if Adobe changed its pdf format, or Microsoft ceased to exist? We will no longer have access to our data. Is that scary or what?
Our ancient ancestors left indelible traces behind them using indestructible monoliths and colossal granite structures. We can still read the hieroglyphic scripts on their walls today. Funny calling them scripts! I wonder how long will our JavaScripts be readable for?
My grandmother had a shoebox full of old sepia toned pictures. Those pictures still exist today, some are almost hundred years old. I wonder how long will the thousands of digital photos I am taking these days will last. I don't even bother backing up my hard drive. What if I lose all that?
I know what I am going to do. I am going to sift through my many gigs of pictures that I took, then pick the best few ones and print them at Sam's Club. This way I can keep them in a shoe box so that my grand children might get a chance to see them.
As for the other data, I don't know how I am going to prolong their existence. I feel worried that all the digital data I have is going to be lost some day. How do I preserve all my programs and documents? I hardly make hardcopies anymore as I depend only on the files I have saved on my hard drive. The most I usually do is copy the files to a flash memory or a CD. Floppies don't exist anymore, so will the CD's have a better luck? Are DVD's still going to be around twenty years from now?
The nagging question is how can I leave documents that could still be read two or three generations from now? Shall I print them on paper? Publish them on microfische?
I wish I could etch my data on a huge monolith carved out of granite. I bet you that would stand the test of time for a while, unless a nuclear war erupts. Even then, I think the monolith is going to have a much better chance of surviving than any of the electronic data saved in the forms we know today. What do you think?