The I2C is only for short wires (within an apparatus).Do you want to use long wires ?
A power loss will make the slave react to 0x00 ? What if three slaves have power loss.If they are the same devices with the same timings, the master thinks there is only one slave, and sets it to a new address. But all three have now the new address.
What if someone pressed the button on three slaves simultaneously ?
The thread right befor yours have some useful information that directly relates to your project:http://arduino.cc/forum/index.php/topic,128361.0.html