Awesome question. Replacing it would be worse of course (because then not even the old timers understand it). One thing i liked about google docs?? Was automatic save, maybe this is the trend. If you take a 5mb picture on your smartphone there is no question do you want to save it. Space is cheap.

But if i really have to come up with something, I'd say green arrow pointing up. Meaning 'upload to your (own private) cloud'

I don't care what the icon is -- just ensure it has a label that says "Save" or something similar ...