How about requiring patent-holders to show progress on their invention every X years, so that inventors can't just sit on an old and important patent they own?
Or, a more ground-up restructuring: what if owning a patent didn't give you full ownership of the technology, but just X% of profit made from it for X years after filing?
With this setup, you could further incentivize progress by granting an additional X% to the first one able to bring the technology to market.