IB Pros: newer tech, less power consumption, faster at stock speeds compared to SB Cons: Heat issues when OC, less capable OC unless you're pro at it and knows exactly what to do
SB Pros: Great to OC, more user friendly to OC, and when OC, performance is very similar to IB that it is almost negligible, no heat issues in air, stable Cons: More power consumption, one generation old
So, if you ask me, I will choose SB if you're new to OC and IB if you either want to keep your CPU at stock, you're pro at OC, or you plan only to do mild OC. As for phasing out the socket type, IB is the last LGA 1155 CPU. The next generation will be a different socket type (not sure what it would be).
In my opinion stick with the SB as IB is only a small upgrade and not worth the extra cost.