Google glass is doomed to fail because it's simply just not a "cool" product, see below for a particularly funny site:
I remember when the very first iPhone came out (I got one right when it came out). I would take that thing to a bar and everyone would want to play with it and test it out. It was "cool" and you definitely wanted to show it off.
Now, if someone went into a bar with Google Glass I think most people would just chuckle or openly point and laugh. I know I wouldn't be caught dead with a pair of them on, that's for sure.
There's nothing Google Glass can do that a smartphone can't, and even if it's slightly more efficient for certain tasks, only social morons are going to eschew looks for a very slight bump in productivity.
Sure, some nerds and technophiles will buy them. But will it become a mainstream accessory like a smartphone? No, no way; not even close.