Actually, if your i7/16gb/1070 machine is a x58 chipset motherboard you might just want to hold out, since the newer stuff is not that much faster in regards to bus speeds and data transmission to SSD/memory. Those two are about 90% of a machines speed outside of the processor. And the processor can usually be updated to a modern-gen Xeon with 6 cores, thus 12 threads.
Intel broke the mold with the x58 chipsets and honestly a video card and CPU upgrade brings them right into current specs... Heck, if you need, you can add USB 3/3.1 cards and anything else via PCI-e.
I have 4 x58 machines at home here, one for myself and 3 for the older kids and with video card upgrades they don't need anything (running @ 4.0GHz, 16-24gb RAM, SSDs, GTX980s). My machine still has dual GTX480s with 3 1920x1200 monitors for 6070 x 1200 video, but I will be going with dual GTX980s based on price alone, along with a 42" 4K display above the triple screens for video editing. I already have dual 480GB SSD drives and 7TB of storage locally with 32GB of ram and will just be upgrading to a Xeon 6-core. I have a 32TB main server in the house so storage is not an issue. I have plans to upgrade the server to 48TB next year.
But, honestly, I really don't think newer motherboards/processors/memory offer that much to justify a $1500-3k upgrade if you have a X58 based system already. Intel knows this, that is why they killed support for it back in 2013. I mean Intel has always supported chipset platforms for 8-10 years+, yet they kill support for the x58 after 5 years??? They knew it was a long-term viable platform.
I doubt we will see such engineering on a consumer level again. Look at the nVidia GTX480s, same difference. Sure they generated a lot of heat, but two or even three of them performed great all the way until they obsoleted it with DirectX12. In the case of those nVidia even released drivers that purposely killed those cards to get them off the market.