What is the probability of an unquestionably superior design being found?
That would be impossible to quantify within a finite timeframe, but approaches 1 with infinite time. A better question would certainly be, "what are the odds that Bitcoin survives for the 120 year inflationary period?" I would, honestly, give Bitcoin some low odds at this point, for a number of reasons. But that isn't really important for the adoption of Bitcoin in the present. After all, the US FRN has not lasted 120 years yet.
Of course, I know this sounds ridiculous.
Indeed. If a true "matter de/compiler" were ever developed, there would likely never again be a need for a currency as such. The 'scarcity' aspect of products sold for such currencies would be forever destroyed, and limited only on the availability of energy.
So the question is this: if BitBox existed, would the market value of BitCoins literally drop to zero? I tend to argue yes. There would be a mass exodus from BitCoin over to BitBox (because BitBox has successfully bridged the virtual-to-real gap). So, from an investing standpoint this is not good as the buyer's market for BitCoins would literally cease to exist, and anyone long BitCoins would be left with a very tired CPU and some worthless data.
I would say, no. If only because the timeframe for the adoption of any widespread technology does not occur instantly or equally across an entire economy. Bitcoins my suffer via irreversable decline, but there would not be a sudden, or mass, exodus if the value was already reflected within Bitcoin.
Being an entrepreneur, I want to provide solutions. Perhaps there will be a market for "design insurance." This would be very similar to a Put Option. What should the premium be for, say, a 10 year Put Option at the current exchange rate?
Again, an unquantifiable risk over any finite time frame. This would be vastly more difficult than, say, earthquake insurance; considering that there is no comparable precedent to base any calculations off of. I would seriously doubt that any costumers could be found, even if the risk could be defined.