I don't expect google glass to ever become popular for everyday use but do think it will have niche markets but the reasons that Marcus thinks it will fail are completely flawed.
I've never seen anyone use bluetooth and then put it away or have it away and then put it on just for a call, from what I've seen people either leave it on all day looking like douches or put it on the entire time while driving. ie. if they have the headset with them then they are wearing it.
He says segways are lame because they are rational which makes absolutely no sense - segways are completely irrational. How are you going to get to work 20 miles away on a segway? You're not. How would you carry groceries home on a segway? You wouldn't. How are you going to transport very young children on a segway? You can't. Segways are toys for the rich and tourists that rent them. They have extremely limited practical usage that is better accomplished with things such as mopeds, bicycles, skateboards, skates, or even good old fashion walking.