No, it is a common misconception. A new standard will probably not change C a huge amount to the casual observer. it should certainly maintain backwards compatability whereever possible. What it will,
most likely do is standardise certain extensions (some POSIX C extensions spring to mind) which are commonly used.
Bear in mind a standard is exactly that - a document detailing the language. This is nothing to do with the practical side of things (compiler writing) at that stage. After the standard has been finalised and released, then it is up to the compiler writers to implement it... implementation is simple compared to creating the standard