Erm...bf4 on ultra with streaming may be pushing the bounds of that pc.
Did you buy it all yet? because some changes can be made.
Spending about $50 more would get you a 970, with a 970 you could even game at 4k on low settings
If you're willing.. a 970 is worth it. Like what Alex said, but not sure about 4K gaming.
4k gaming isn't that crazy, you can game with a 270x on low 4k.
Not saying that the OP should 4k game.. I wouldn't even recommended it till better cards come out. I'm just saying that it'll be worth it because streaming can hit performance from what I've seen, and that it'll last longer.