No, and if you think that's what getting NaCL running will take, it explains a lot about the quality of Mozilla's technical output.
First, the NaCL runtime and tools are NOT tied to Pepper. You could take those as-is and have the hardest part of the stack done.
Second, Pepper is NOT a complex API, and anyone arguing that it is completely nuts. It provides basic abstractions around sound, 2d/3d rendering, etc. If anything, it's a relative simplified SDL equivalent.
If that's hard to implement/integrate into your environment (including thread safety issues inherent in its support for threads), that says more about your browser's architectural issues than it says about Pepper.
Are you serious? You're measuring complexity by header file count?
I'm sorry, but that's small. By that ridiculous metric, I have numerous projects that have involved a few man months of effort that far exceed '66 headers' worth of complexity.
Of what? The entire Chromium browser?