What do you mean 'will cause' - it has already happened. Almost all children learn English in Government primary school in Europe, and quite a lot study at pri

What do you mean 'will cause' - it has already happened. Almost all children learn English in Government primary school in Europe, and quite a lot study at private schools with the entire curriculum in that language. The legacy local language is basically treated as a secondary language, something to use for gossip and low-level transactions with local businesses (bars, supermarkets, plumbers). Many Governments offer services in both languages: paying taxes, driver licensing, etc. What is the point of becoming highly fluent in a legacy local language, even for someone born in that country - to write books and articles that no one (in a global context) will ever read? Fluency in English delivers so much more, has many more learning resources available, and is a much better investment of school time.