Well, technically DVCSes like git use "blockchain" (the repo, logically, is pretty much a chain of blocks that incorporate the hash of the previous blocks - just tree instead of linear dependency).
So we are already successfully using blockchain for decades just not as... currency provider.
Forward secure sealing (used in logging) also have similar idea
The Merkle tree used by git is only a component of blockchain. Also in three or four years blockchain will have been in use for decades itself (i.e. two).
So we are already successfully using blockchain for decades just not as... currency provider.
Forward secure sealing (used in logging) also have similar idea