It's possible the relay network could be subverted by a large number of colluding relay nodes. Thus there's a second check: future miners refuse to include dishonest blocks in newly mined blocks. If you want your generated coins to mature, your blocks have to be legitimate.
To prevent a 51% collusion attack, a third safety is possible: create a "decentral bank". This would be a second mining system where people perform proofs-of-work solely to manage monetary policy, which means authenticating price quotes and the inflation rate.
The fourth safety is the strongest: anyone can verify that the price quotes in the block chain are correct, and the inflation rate responds very slowly and smoothly. If it becomes apparent that the system is being gamed, we'll have time to figure out why and how before coins start being generated excessively. We then release a new version that adjusts whatever is necessary to close the loophole. In the worst case, we revert to 50BTC per block.
While these kinds of ideas are interesting, they are rather forced. The system I proposed for EnCoin encourages the people using the system to do whatever is best for the system. Separate mining from trading so that mining does not secure the network. Use a merchant-based system of reputation that is increased only via economic activity in the form of losing money to a transaction fee that is refunded based on increased levels of reputation. As more and more merchants want their transaction fees refunded, the limited pool of reputation awarded per day becomes more and more difficult to obtain, thus making it harder and harder for a malicious group from gaining >50% of the reputation. This reputation is used to secure transactions and mining blocks rather than hashing power. Even if an agency gains 50% of the reputation, the "cloudnet" or average peer nodes (who, with the reduced bandwidth at high transaction volumes vs bitcoin should be available to anyone with a decent internet connection) will reject any bad transaction blocks or modifications to the network. Even non-cloudnet peers can detect malicious modifications and will not transact on the bad half of a network split (something that is possible because of a tiny consensus block in lieu of a gigantic block chain).
The goal is a stable price based on encouraging mining only when it is profitable since it doesn't secure the network. There is no limit on the amount of coins per hour or day, but the system will keep track of how quickly the coins were produced to increase difficulty, as well as fostering competition among more efficient machines by occasionally lowering the award so that improvements in energy usage (or even reductions in the price of energy) can be accounted for in the difficulty, then the award increases again with a new difficulty.
The money supply can grow as the economy grows. If the economy outgrows the supply, hoarders/savers are encouraged to sell for the immediate profit because otherwise many will take to mining and bring the price back in line with its cost to produce. Any unrefunded transaction fees are spread out to all holders of coins so that in the rare case of an economic contraction, those who saved had earned interest previously and will continue to earn interest off of those new to the system who do not care that the value may not be what it once was and will still transact. On top of this, merchants are required to hold a certain amount of coins to become reputable members of the tradenet, so that creates demand and a high cost for an agency wishing to subvert the reputation.
I think it is a system that merits more discussion, especially if you are looking to fork bitcoin to solve its many issues. A stable price is key to getting merchants on board, and merchants are the key to a successful economy.