pcie 3.0 is not worth it. current cards do not hit the 2.0 limit yet. if you keep on waiting for the new next best thing, that's all you;ll do. cause there is something new around the corner every six months.
That's completely ridiculous. Yes, there's a new CPU or motherboard every 6 months, but PCI Express updates about every 4 years. Making the wait worthwhile.
And yes, nothing can saturate PCIe 3 today, but in a year or two, as your own post suggests, things will have changed significantly. You can always plug a new graphics card or SSD into your build, but you can't plug a new PCI Express architecture into your motherboard.