Thats a good comparison for the blockchain and the new currencies how ever I am surprised why you did not call Google as the big island. Haha. Well, its true that crypto currencies have this kind of status now as they are becoming the big data centres everywhere. They are creating huge number of blocks per seconds which are having XY data packs in it forever. Well this can now be used for the storing of critical information, SSL certification and much more things !! I guess soon blockchain will have great importance in the big data companies like Google as it is the only chain that can sustain so much data that is being generated by world. I guess there are big logics for sure.