Yes it's replaceable. I've used it with newer builds from the open source project. They even provide binaries and instructions: http://clang-analyzer.llvm.org/xcode.html

If by replaceable you mean using some other analyzer, I'd say it's not easily replaceable but if you can produce an analyzer that produces similar output and that's has the same options, then sure. clang in fact did that sort of thing with their gcc driver.