So question is would or could the 560SLI setup cause a bottleneck and if so how likely will it happen?
What resolution are you running at? Is there a multi-monitor setup involved?
Which games are you looking at? Different games stress the CPU/GPU to varying extents.
Also bear in mind that different games benefit from SLI to varying extents.
The 560 Ti in SLI is quite a powerful combination, its quite likely to result in CPU bottlenecks for MMO games like Skyrim.
Shooter type of games (Battlefield 3, Crysis) tend to stress the GPU more than a CPU.
That said, your CPU is no slouch - its only about 10-15% slower in gaming than the i5-2500K, which is a strongly recommended CPU for gaming (http://www.anandtech.com/bench/Product/47?vs=288
compares the i7 940).