This could possibly slowly curb some of the shit postings getting upvotes. But it could also not. Auto-voting on popular posts is still a pretty safe bet.
The whole idea of whales and minnows voting is based on the current system. Unless it were a hybrid model that slowly sucks away your steem, they would become based on who is more willing to risk a vote, rather than who has more SP.
It might be good though. Essentially you're turning the voting system into a tip betting system. You put forth money on a post you think is good, and then hope you can get paid back.
It would have to work on steem or steem dollars as well, as if it sucked away SP, that would be introducing it back into the system prematurely, and might have negative consequences. You could power down your account by voting it away.
It would also likely mean that we shouldn't make accounts for free. At least not the ones with any voting power. Maybe they'd cost a few bucks, and come with a bit of voting power built in, and then everyone could set the amount their vote costs.
I think I might be willing to have paid votes. I'm not sure others would be. Especially in poor nations.
I'm not sure this is the solution, but it's interesting.