The real question is will your needs in the phone change in the next year or two? If not, then it doesn't really matter what comes out in the immediate future. To be honest, outside of video chat and gaming, I use my iPhone 4 in almost the exact way I used my AT&T Tilt that I bought four years ago. My needs haven't changed much and I would suspect that the needs of others haven't changed too much either nap if the device that you have chosen today is the beat on the market and it meets your needs, then there is a good chance that it will next year and the year after.
I agree with your post. Desktop PC's with quad-core chips hit the point 2 or 3 years ago where I had zero reason to upgrade in the foreseeable future. And ditto laptops a year or so ago.
I think I reached that point with phones with the EVO 3D (now my wife's) and Photon. The Photon is physically as big as I'd want to go for a phone, has a dual-core CPU of which I rarely even activate the 2nd core, as much RAM and ROM as I'll use for the foreseeable future, and a high-res screen where my eye isn't capable of seeing pixelation.