.CO instead of .COM? I don't think so.
I can't picture this becoming big. Much like other, newer top level domains such as .me, there are two many hurdles to jump over to gain acceptance. I run a .me site and the biggest question I get is "There's a dot me?" Think of how hard it has been to get even a small percentage of people to understand that there's a .tv.
Bottom line for businesses and domain name investors alike: .com is going to stay the gold standard and the default "web address" in people's minds for years to come, at least in the English-speaking world.

