What will be my next bottleneck?

I see no bottlenecks here.Your specs are very well matched.(Of course,OC'ng the CPU will help in some games,but keeping it at stock won't cause any slowdowns etc.)

Bottleneck for what? This depends entirely on the usage scenario in question.

For gaming, strange though it might seem your GPU system will still be the bottleneck in most situations. Even with a system as powerful as yours. This is especially true if you overclock your CPU to its maximum potential. It is technically true that your CPU might sometimes be the limiting factor in your frame rates, but this will probably only be in circumstances where the frame rate is so high that a CPU bottleneck is of no practical relevance. I'm of the view that the performance of a system in games should be judged by the minimum frame rate rather than the average. In complex scenes with all the effects maxed and with a high draw distance, the part of your system that determines the minimum frame rate will still be your GPU.

For video editing or transcoding, your bottleneck will be entirely your CPU. For disk intensive operations like booting, your bottleneck will be your SSD.

Storage space, unless there's more you haven't told us about.

Beyond that, that is one top spec machine that will handle anything, except heavy video editing.

Make it game better?! What resolution are you gaming at that 2 x GTX 680s and an IB quad core w/HT won't cut it? Multi-monitors?

I have an extra HDD with 500GB just for storage, and i'm using a NAS server at home.. so storage won't be a problem..

I'm using it for real high-end gaming.. i play most of the new games and want them to run at max settings..

Currently using 1 monitor @ 1920x1080.. and i'm considering 2 upgrades.. Upgrading it to 1 1920x1080 3D monitor, or 3x1920x1080..

Playing atm: Metro2033, Battlefield 3, sometimes Aion, League of Legends (little overkill, but a fun game  ) and i'm planning on playing GuildWars2 a lot

Going to a 3 monitor 5760x1080 gaming resolution overall performance will be limited first by your GPU and next by your CPU.

So most likely my GPU's are my first bottleneck, and my CPU will be bottleneck after that.

To be honest - I agree with Maziar. You have a nicely balanced system.
A bottleneck would be - you can't run the game well enough to enjoy it. As in it won't run at all.

Increasing the effective resolution IS going to change things but you CAN adjust your game's performance to keep it running well and still have an enjoyable gaming experiance.