First of all It is theoretically impossible to run out of upvotes as it takes a percentage of your voting power every time, always leaving some. Also It sounds like you will be leaving money on the table by not using all your down votes. The more you down vote the more it cancels out the rewards allocated, which in turn leaves more rewards for posts not down voted. This means people will down vote just to down vote. This is going to turn into a viscous place with this in place, causing lots of drama, on probably having many people leave the site. I for one will take my investment else where. You will lose active users, and then advertising revenue will go with it. You will be sliting your own throats worse than steemit inc has already done. Is there nothing else more important you can work on... Maybe SMTs, communities... Keeping people here.