That's why you do research ahead of time when buying a phone to see rumored and upcoming devices
. I always do this, and did this when I wanted the Droid X. After everything, I came to the conclusion that the Droid X had everything I could ever want in a phone and more, and the next android devices coming out wouldn't be too big of an upgrade for my needs.
Also, this is why I haven't bought a new laptop in 5 years. I can't justify spending the money when so much new technology comes out so quickly, especially with computers. With phones it's easier because what I do is change up every year or so and sell my old phone and get the 199 deal from Verizon. So it really evens out in terms of price.