Of course, I also don't know what a "world on the blockchain" would look like, since this technology has just made its first, still somewhat unstable, steps. This is just one of the cases where, as far as I'm able to see, the benefits and opportunities could, with high probability, far outweigh the risks and downsides.

A lot of things can be expected to change, both on the surface level and more fundamentally, similar but perhaps even more significant than another emerging layer of omnipresent code, i.e. the "Internet of Things" (of course, even outlining the ways IoT and blockchains could intersect and interact would require at least an entire post).

A world saturated with strings of code, implemented both in the cloud and as physical objects, running most of the interactions that today still happen at human speeds, each accountable and subject to review in its ledger but at the same time most of them carrying encrypted data of which only the source and destination, but not the content, can be determined — certainly a few steps apart from the world we are used to see now but perhaps not all that much. Most of the preliminaries of these things are already here and working all around us, just not made fully explicit yet.