Longevity is a difficult animal to handle... Six years ago I built my current rig, with a then new socket LGA775 motherboard. My choice for CPU was the Intel Core2Duo E6750, which I thought would serve well enough. As it did. Last year I sold it in an Internet auction where I found an E8500, the high end dual core CPU for LGA775. During the years the price difference between the two processors had dropped down to €30, paid €70 for the E8500.
My point is, any socket will outdate some day. Some do it faster than others and we can't tell their life span beforehand. For LGA1150 we know there's many more expensive processors, like i7-4770K Haswell which today costs $339 at Newegg. I suppose when it's time to get some more oomph something like that can be found at a reasonable price.