kisby, I think what is being suggested is that it's better to just deal with it yourself by selling your old phone. It's sort of like the difference between buying a car and leasing a car. You'll do better buying it, but some like the no-hassle of leasing.
Personally I'm a lot different than you. I don't like the hassle of changing phones all that much. I would note that a lot of S3 owners are apparently seeing little reason to upgrade to the S4, so it may very well be that in a year you won't want to upgrade. Just dealing with it yourself (e.g. selling your old phone and not having Edge) will give you that option.
Finally, I would note that as smartphones mature, the technology will start changing more slowly. I remember when a 2 year old computer was ancient, and now a 5 year old computer is still more than adequate. Same thing.