It seems important to construct a market-based lottery system, where the payout rate (incidentally, proportional to the rate of Ether inflation) will be determined by market demand for computing power.
This solves two problems:
1. it incentivizes Ethereum compute supply to keep up w/ demand for computation
2. it ties the rate of Ether inflation to Etherium computing demand. This creates a rate-limiting mechanism — effectively filling the job of a traditional Central Bank in maintaining a money supply commensurate w/ the level of economic activity in the Ethereum system.