No need to count leading zeros. If the common denomination gets that small, people will naturally migrate to millibitcoins and then eventually to microbitcoins.
Why count the leading zeros in 0.00126 BTC, when you can simply refer to 1.26 mBTC.
I'd certainly expect to see a price of 2.83 µBTC rather than 0.00000283 BTC (or at least I'd expect it to be displayed as 283 satoshi).