They can of course break it any time they want but since 1 gigabyte in storage space costs, what, a handful of glass beads nowadays, do you really think enough people will bother with this to cause serious scalability problems for a search engine company that handles a hundred million hits per day?
Yeah, 1 gigabyte of storage costs a handful of glass beads.
But do you really think it will stay 1 gigabyte of storage?
It took this guy only 3 days to hack up this program in python. Give him another three days and he could make it register a dozen accounts and link them together transparently into one filesystem. In fact, it scales pretty easily to the point where I could have unlimited storage on Google's servers--and then it would be a problem for them, and they would have to break it.