I don't know what you mean by "image chips" - are you talking about the sensor? It's not so much the sensor as the firmware. Color depth is how many bits are used to represent a color. Most cameras have 8 bit color. The newer ones have 12 or 16 bit color. 8 bit color has something like 24 million colors where the 12 has 36 million and the 16 bit must have a bunch more than that!
The important thing to remember - most of the devices you use for output (like printeres) can't do 16 bit color. So you'll flatten it to 8 bits to print it anyway. It's an interesting development - but nothing to blow a bunch of money over until there are more and better devices to view and print in 16 bit.