no oral modification clause

[Hutz_and_Goodman]

If there is a NOM clause in a contract that does not require compliance with the statute of frauds (for instance, sale of goods under $500 or common law contract for services (ex. employee/employer at will contract)), and there is no evidence of waiver, what is the effect?

If a party wanted to modify they would need a writing to accomplish the modification, but would the requirements be for the writing? The standard SOF requirements (either under common law or UCC)?