Yes, we're definitely going to do that at some point. What stands in the way is the cost of storage and bandwidth. We're never going to be able to do it Google-style, keeping your entire project history forever, nor saving to the cloud as often as you'd like. We're considering saving a version or two in browser storage on your computer temporarily, and maybe keeping one autosave in the cloud every 10 or 15 minutes, something like that.
And we already save two of your explicit saves: the one before last and the one that was current at the beginning of today. See page 39 of the manual.