It may be a little less spectacular in the 'Wow' factor, but the Apple Watch is doing the same thing with watches (something many, many people use) and fitness bands (something a growing number of people use), that the iPhone did with cell phones (something many, many people used) and MP3 players (something a growing number of people were using). It took the two basic functions and put them into one device, while adding other functionality not really thought of for either of the legacy devices.
For years prior to getting my first iPhone, I had a cell phone (which also took pictures), and an iPod and didn't like having to carry two devices - I wished for someone to make a device that would cover both functions. The iPhone did just that and more. Late last year, I was in the market for a new watch, and was also interested in a fitness band. But I didn't want to wear two devices. I splurged and got the Apple Watch. It combines the basic functions of both devices, and adds other functionality. Some of which I don't care about, but some that I find useful. Overall though, I'm very happy with the decision and my use of the watch is growing.
I agree with you - smart watches in some form have a future. I don't think it will be as huge as smart phones, but I see a lot of potential.