One of the challenges of a new currency has always been the need to artificially increase the "difficulty" by requiring a HUGE amount of erroneous calculations. Bitcoin's hashing is terribly wasteful, while PoS coins end up being super-deflationary by continuously reconcentrating the money supply.
What about a mining system that is entirely based off the successful execution of the script attached to contracts, plus some multiplier on the fee (eg 1.05)? This way the computational power given to the network would reinforce the network itself.
This has the added benefit of maintaining inflation on par with actual economic processing need, rather than some arbitrary percent or number.