A few people back in 1492 probably said the same thing about the New World. Did you read the part where there's enough water to cover the planet in earth-like oceans? If we created some genetically-engineered primative life forms that could live on Mars we could eventually turn the place into Earth II.
They may not even find traces of water. This was discovered from orbit, not from actual samples.
They wasted no time using this discovery to call for a manned Mars landing. I'm not saying there is no water on Mars and I'm all in favor of exploration, but this sounds more like a play for more funding then an actual discovery to me.
Why are you so certain they will find no sign of life? Where in the bible did it state we were the only place life exists? They have found life in the depths of ocean vents and in deep core samples from oil wells all over the world. Why not on planets too? Maybe God put them there for us to have dominion over them too, as soon as we figure out how to get there.