A lot of people talk about dead sockets, (end of life) and upgrade paths without much context, just to add and expound.
Yes, Intel is set to use a new socket sometime this year, but its not like if you built a system today with the current LGA1155 that as soon as Intel does your computer will be rendered effectively useless. Acura stopped making my car (RSX) in 2006.. Does that mean my 2003 model no longer operates? Don't be silly, of course not.
An Ivy Bridge LGA1155 assuming you choose the right model to meet your needs in the first place (another jab about people who talk about upgrade paths)... The system will last you 3-4 years, which is about the most extreme one should expect a computer to stay at peak usability. And again, I have computers older than that that I still use today, yes they're a little slower as software demands on the older hardware have increased, but still functional. Buy a computer or computer components for what they can do for you today rather than try to buy up on parts because you think they're more "Future proof", its cheaper and you will get better satisfaction overall in the long run.