I've been building or upgrading computers for 20 years and can't recall upgrading a CPU. By the time I want a new CPU I want a new motherboard. The old stuff just gets pushed down the pecking order. At the moment, I'm third in line in my family.
Well AMD has been pretty good at sticking with a socket for an extended period of time, look at socket A and super socket 7. Socket 754 was just meant to be a segway into a socket 940 platform, but AMD found for some reason that socket 939 was a better platform, but its funny now they are going back to a enhanced version of socket 940 in the M2.