Just a curious question...
Will this build bottle neck anything?
Im also waiting to buy a different 21:9 monitor once they come out with higher refresh rates for them..
Only your wallet.
This thing looks good to me! I would suggest either 4k 60hz or 1440p 144hz+ given what you have but this looks pretty good! Also - check out the Kanto Yumi speakers on Amazon - a little bigger but IMO better speakers than the ones that you have picked out. A lot of people also say the M40x are better than the M50x, I have the M40x's, but I have not actually been able to compare them myself.
There will always be a bottleneck somewhere, and what part depends on the program.
There are a few tweaks I would recommend:
Don't get the Black drive. Get two Seagate Barracuda 2TB for the same price, then RAID 0 them. 4TB of fast HDD for the same price.
You might as well get the fastest RAM you can. Infinity Fabric scales with it. https://pcpartpicker.com/product/V398TW/gskill-tridentz-rgb-32gb-4-x-8gb-ddr4-3600-memory-f4-3600c16q-32gtzr
Get a full version of Windows so that it isn't tied to the motherboard.
You can get the newer G3 for less money: https://pcpartpicker.com/product/PvDzK8/evga-supernova-g3-850w-80-gold-certified-fully-modular-atx-power-supply-220-g3-0850
Or you can get a higher efficiency unit for a bit more: https://pcpartpicker.com/product/74M323/seasonic-prime-850w-80-titanium-certified-fully-modular-atx-power-supply-ssr-850td
No problem! Good luck with your build!