Upgrade Planning Guidance Needed - CPU, GPU, and Monitor

[admiral_tuff]

Hi everyone, first time posting and I'm considering various upgrades.

I am not sure where my current bottle neck is, but I am looking to upgrade my PC bit by bit. I'd like to achieve all three of the upgrades listed below over time, but I'm not sure the order to go in, or if these are even good choices.

Current build:

• 
  CPU: Intel i7 2600k @ 4GHz OC
  MB: MSI P67A-GD65 (B3)
  RAM: 16GB DDR3 Corsair Vengeance 1600 MHz (PC3 12800)
  GPU: EVGA GTX 780ti
  PDU: 800w
  OS: Windows 10 Home on 256GB SSD

Potential Upgrades:

• 
  Intel i7 Processor (6700k, 6800k, next gen?) + Motherboard + RAM
  GTX 1070/1080 GPU
  LG 34UC88-B Ultrawide Curved Monitor

Additional Question:
Will my current build run games well at 2560 x 1080 on the ultrawide monitor until upgrading the GPU to run at 1440p?

Will the GPU upgrade be throttled by my old CPU?

Is the CPU upgrade even necessary? Most sources I've see say the old Sandy Bridge K models are still viable. I kind of want to hold out til the next gen Intel architecture, so ideally the CPU would come last unless it is a major hindrance.

 

[nostall]

Re. your 780Ti, it should do just fine on your ultrawide 1080p monitor, maybe even a 1440.
http://www.geforce.com/hardware/desktop-gpus/geforce-gtx-780-ti/specifications

Regarding the CPU etc. upgrade: I don't know if that CPU will hold your new 10xx card back, but my instinct tells me that it would; I am sure others here on Tom's can tell you a bit more about this issue.