This means that the "supply" of bitcoin has just shrunk by 700,000, which is like over 4% of total bitcoins. This means each real bitcoin remaining is now more rare and thus valuable.
In what world is 4% of 21,000,000,000 only 700,000? Your math is completely wrong, 4% of 21 billion is 840,000,000 which is orders of magnitud higher than a partly 700,000 (in comparison).
And if you're talking about the total minted Bitcoin in circulation then your math is still completely wrong, 4% of 12 million is 480,000 which is significantly less than 700,000.
They lost roughly 6.2% of totally minted Bitcoins in circulation and roughly 0.0062% of all the Bitcoins there will ever be.
In the short term, it might make prices rise; if (and only if) the market shows it still has enough confidence in Bitcoin, but in the long term it's not a very large percentage to affect anything.
P.S.: I wish more people would at least try to do some math before posting misinformation concerning numbers and percentages...