Has no impact on day trading if you go flat every day. You actually have three days to be flat. In essence you still have the ability to write your very own personally guaranteed 3 days single stock futures contract. What you can't do is let it run longer than three days without having your position squared and secured... Buy or borrow just make sure its done within 3 days and all is in compliant. Just impacts players that short volume that they let run unsecured and cash out when they are in the money. The scheme they really want to stop is averaging down by selling more naked shorts until the market is dilluted driving price down for an exit. The curves for price appreciation versus depreciation greatly favors averaging down shorts over longs.