Unless you plan to stream at very high quality on low bit rate, the 6700HQ should manage.
Only in case of streaming AND heavy CPU games it might be problematic .
In general, it will slightly bottleneck the 1070, but not enough to warrant getting another CPU (by bottleneck I mean that another CPU might give you some extra FPS but in VERY few cases and in VERY little amounts).
What do I mean?
I mean that if for example you are playing Farcry4 and at the same time your antivirus starts a scan and you are in an area that farcry4 suddenly needs a ton of CPU power, you might see a higher FPS drop with a 6700HQ than another more expensive CPU, but in both cases the drop would be there, it would just be less of a drop. This is more a problem of the game using the CPU poorly than a problem of hardware itself.
Meaning the benefits of a more expensive CPU are so few, that it is mostly a waste of money.