Flexibility within a norm permits non-destructive internationalization of the language. For most people the purpose of learning and speaking English is to communicate with others who also speak English. Regardless of how far removed English may seem to be drifting from the native form, out of necessity, boundaries will remain, providing a norm simply because the ultimate purpose is effective and efficient communication. There is no cause for concern that the pronunciation and grammar will be turned on end and that the English language, as we know it, will be hopelessly rearranged. On the contrary, the English language stands to benefit from this international interaction with the influx of fresh terms and phrases pertaining to new ideas and concepts.
Infinitesimal changes occur in every act of speech, and mostly make no impression.
Now and then a scintillation is captured and held. We hear a novel expression and like it. It is adaptive - fits a style or names a new object or expresses an idea succinctly. The equilibrium is temporarily upset but reestablishes itself quickly. The new expression, like an invading predator, marks out its territory, and the older inhabitants defend what is left of theirs.