I agree with Coozie here. As resolution increases, the games become more bound by the GPU rather than the CPU. Not to mention, considering you were looking into streaming, as a fellow 2700X user, I must say the thing's a beast when it comes to handling streams. There are a few things I'd change though- Ditch the HDD. It's only an extra source of noise, and you could replace it with a 1 TB ADATA SSD paired with a 250 GB 960 Evo for booting, all around faster mass storage for nearly the same cost.
Speaking of noise, I also noted that there wasn't an after-market CPU cooler on that list. While the Prism is certainly thermally capable, if you want reasonable temps, the thing gets pretty loud (Im speaking from experience.) Go for a Dark Rock 4 from Be Quiet, it's a fantastic unit. As far as the keyboard/mouse are concerned, that's entirely up to you. Be sure to do your research, as peripherals are subjective in nature.
PCPartPicker part list:
https://pcpartpicker.com/list/88tjGG
Price breakdown by merchant: https://pcpartpicker.com/list/88tjGG/by_merchant/
CPU: AMD - Ryzen 7 2700X 3.7GHz 8-Core Processor ($309.90 @ SuperBiiz)
CPU Cooler: be quiet! - Dark Rock 4 CPU Cooler ($67.99 @ SuperBiiz)
Motherboard: MSI - X470 GAMING PRO CARBON ATX AM4 Motherboard ($174.99 @ Amazon)
Memory: G.Skill - Trident Z 16GB (2 x 8GB) DDR4-3200 Memory ($184.89 @ OutletPC)
Storage: Samsung - 960 EVO 250GB M.2-2280 Solid State Drive ($112.78 @ Newegg Marketplace)
Storage: ADATA - Premier Pro SP920 1TB 2.5" Solid State Drive ($184.99 @ Amazon)
Video Card: EVGA - GeForce GTX 1080 Ti 11GB FTW3 GAMING iCX Video Card ($799.89 @ OutletPC)
Case: Fractal Design - Define R6 Black TG ATX Mid Tower Case ($109.99 @ Amazon)
Power Supply: SeaSonic - FOCUS Plus Platinum 750W 80+ Platinum Certified Fully-Modular ATX Power Supply ($109.90 @ Amazon)
Operating System: Microsoft - Windows 10 Home OEM 64-bit ($99.89 @ SuperBiiz)
Monitor: Asus - MG279Q 27.0" 2560x1440 144Hz Monitor ($487.54 @ Amazon)
Total: $2642.75
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-06-29 15:25 EDT-0400
As far as the case/fan setup is concerned, the R6 has great stock fans, although you can replace them later if you find them to be a nuisance. There's only a 2 Db difference from them and the silent-wings.