Ex. I mine a Contingent Block today. The Coins in the Contingent Block become a bitcoin Block on August 1st 0:00 UTC or Block xxxx if difficulty is less than X, and disappear otherwise. In the meantime, I can trade the contingent coins on an electronic exchange similar to bitparking.
Now note that (barring changes to mining tech) difficulty on August 1st [or block xxxx] proxies for the USD/BTC exchange rate on August 1st. The difficulty price relationship will only become stronger over time, once the mining business is more mature. Thus if I trade some bitcoin for some contingent coins, I could remove a considerable fraction (probably the majority) of the variance in the USD value of my BTC holdings as of August 1st. The insurance relies on a p2p system with block chain integrity as the only counterparty. It would be much, much cheaper to use this system for insurance rather than a traditional market which exposes users to counterparty risk.
Difficulty of regular and contingent Blocks can be pegged so that the total number of coins and contingent coins generated at block time t is fixed in all future states of the world. Fixing the generation rate would make contingent claims a scarce resource, i.e. contingent claims would not affect long-term money supply trends. Relative difficulty for each coin type would be adjusted according to a system of linear equations that related past difficulty levels to current difficulty and which incorporated the constraint that expected total supply generation remained constant (i.e. solution of a system of linear equations)
Alternatively, a p2p contracting system could be implemented which allows bitcoins to be held in escrow by a blockchain and then distributes bitcoins at expiration according to difficulty information in the bitcoin block chain. The block chain would need to be secured using a proof of work system that rewarded individuals performing the work with contract fees. Contracts would need to be standardized (for example you can only contract on ln difficulty >= 0, 0.1, 0.2, .... and only on realization on the first day of each month or week). It is important that each side of the contract could be freely traded to other peers, so that holdings in these contracts would remain liquid.
I am not a programmer, so I don't know which type of system would be easier to implement. Combining everything in one blockchain seems more secure.
Either of these systems would make it much easier for merchants to adopt bitcoin without subjecting themselves to large risks or the considerable expense of exchanging BTC for USD after every transaction. The value of bitcoin is inversely proportional to its velocity. If merchants are constantly exchanging BTC for USD after every transaction, the velocity will be high and BTC value will be low. Instead Merchants could hold BTC and a bundle of BTC contingent claims aka BTC derivatives. If unwilling to bear the residual risks, they could purchase supplementary USD-denominated insurance on futures markets. The value of BTC would still be higher because much of the insurance market could be denominated in BTC.
"Bitcoin is technically sophisticated. As a monetary system, it looks primitive." - The Economist
I think this is a correct assessment. If bitcoin doesn't eventually introduce more sophisticated p2p monetary instruments, some other digital currency will. This currency will be much easier for merchants to adopt. If bitcoin hasn't achieved world domination before this happens, bitcoin will disappear and the new currency will take over.
For a simpler proposal for more basic monetary instruments (bonds), see my post here:
http://forum.bitcoin.org/index.php?topic=18288.0