rhysiam :
I don't think a platform change will be due for a good 5 years or more(look at sandy owners). If the i3 starts to show it's age in two years, you just pop a second hand i7 6700 or i5 6500 in there and be good for another 4-5 years. honestly though, with DX12 coming along, teh i3 may actually become better and not warrant a replacement in two years.
That's a fair point about chucking a Skylake i5/i7 in the system down the track, if you can still find them around.
Most people are hoping DX12 will make better use of CPU cores, which might push an i3 even harder. Though I'll believe that when I see it. But yeah, I see where you're coming from. With the original question I think you can make a strong case for the i5 + 950, because the gap between the 950 & 960 is not all that big. But if indeed the i3 gets you a 480, I'd concede that you're probably right and it's clearly the better choice. If the 480 turns out to be as good as it looks so far, it's just untouchable from a price/performance perspective and so far ahead of the 950/960 that it puts the i3 build on top.