Not really predictable.
Even assuming energy costs stays the same and hashing power / difficulty increase like they used to you'd still have to know how the price will change. No one really knows that and if they did they wouldn't tell you and instead make a few millions. If the price suddenly drops it might end rather soon, if it rises then this might take quite a while. There's also the problem that people might start looking for the next big thing and with everyone investing in the same coin, believing it to blow up soon it will become a self-fulfilling prophecy.
After the slump to 150$ in July we're back to 300$. I wouldn't hold my breath.
Just getting a wafer through the fab takes 3 months, then you should need to assemble the GPU and ship it (in the literal sense) so 4 months is a very optimistic estimate. Also the machines involved in semiconductor manufacturing are so expensive and maintenance intensive and the personnel can't be laid off that it costs basically the same to have a fab running at full capacity as it costs to not do manufacture anything. TSMC/GF/Samsung don't just have more capacity lying around, it's booked months or years in advance, so just giving them a call won't cut it unless you're willing to pay more than the fines they have to pay for delaying or reducing the volume delivered to other customers.
The WD Black is almost never worth it because it's really not that fast. The 1TB version especially wasn't any faster than a standard Seagate Barracuda half its price when it launched and isn't any faster now, since there hasn't been a new version since 2013.
vs old Barracuda http://hdd.userbenchmark.com/Compare/Seagate-Barracuda-720014-1TB-vs-WD-Black-1TB-2013/1849vs1822
vs new Barracuda http://hdd.userbenchmark.com/Compare/Seagate-Barracuda-1TB-2016-vs-WD-Black-1TB-2013/3896vs1822
vs Toshiba P300 (same as DT01ACA) http://hdd.userbenchmark.com/Compare/Toshiba-P300-1TB-vs-WD-Black-1TB-2013/3589vs1822
If you're going for speed buy an SSD.
There is cheaper RAM. Zen is a bit weird and might be faster with lower clocked dual rank RAM instead of >=3000MHz single rank. Could be server optimizations first, could be by design because on servers bandwidth is more important. Read up on it if you want to go down the rabbit hole and search for dual rank RAM.
There are no reviews for the new CX series yet, but it's made by Great Wall, which makes me worry that it's another bait and switch (sell good PSU at a decent price, then switch to a much cheaper OEM once everyone knows they are good). Either way it's non-modular so the CXM series is better by default at the same price. Also there is no way you're going to get that build to 600W oc'd without anything catching fire. 450W are plenty.
As I've said before the 200R is a good 30-40$ budget case and simply not worth it for 70$. But I'm not going to stop you.
CPU: AMD - Ryzen 5 1600 3.2GHz 6-Core Processor ($197.65 @ OutletPC)
Motherboard: Gigabyte - GA-AB350-GAMING 3 ATX AM4 Motherboard ($99.89 @ OutletPC)
Memory: GeIL - EVO POTENZA 16GB (2 x 8GB) DDR4-3000 Memory ($119.99 @ Newegg)
Storage: Samsung - 850 EVO-Series 250GB 2.5" Solid State Drive ($104.64 @ OutletPC)
Storage: Seagate - BarraCuda 1TB 3.5" 7200RPM Internal Hard Drive ($44.38 @ OutletPC)
Video Card: Asus - GeForce GTX 1060 6GB 6GB Dual Video Card ($289.98 @ Newegg)
Case: Corsair - 200R ATX Mid Tower Case ($69.99 @ Amazon)
Power Supply: Corsair - CXM 450W 80+ Bronze Certified Semi-Modular ATX Power Supply ($26.99 @ Newegg)
Optical Drive: Asus - DRW-24F1ST DVD/CD Writer ($17.84 @ OutletPC)
Operating System: Microsoft - Windows 10 Home OEM 64-bit ($89.89 @ OutletPC)
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-08-20 05:18 EDT-0400
Supply and demand. Supply is tight, demand is high. DDR3 is going out of production so supply is soon to be nonexistent.