I used to be one of the people who would refuse to buy something if I knew something newer would be coming out soon. Then, I got my Early '08 iMac for Christmas in 2008. At the time that was, of course, the newer iMac available. Now, the model is 3 years old and still running fantastically.
Sure, when new iMac models were unveiled, I had the natural desire to upgrade and get the better hardware. Nonetheless, I'm still enjoying my 3 year old computer, and it's running great.
I myself purchased my iPhone 4 in March of this year, and am bound by a two year contract. Yeah, I might be a little outdated when the iPhone 5 drops by, but at the end of the day a good phone is a good phone. Besides, in two years time, there will most likely be something superior to the iPhone 5 on the market.