That idea of a system where downvotes are measured through a similar way we provide witness approvals would go a long way. Instead of HivePower determining the influence of a downvote, the community would have to vote for you to have your downvotes have certain power.
Granted someone could just vote for their alt and give it nuking power, so this measure would need some tweaking, but I like it. Either the community gives you the power to downvote hard, or your downvotes is worth pennies.
I think this idea has merit. I think it may require quite a bit of changes to Hive code. But it is just as valuable to the future as other software changes, so hopefully it gathers support.