The future status of English as the global language is assured

Most people in western countries speak English as first language and other countries over the world speak and learn English as their second language. Now, English is the global language undoubtedly, but will it still be the global language in the future is a question. While some people say that the economy of China is booming very fast now and China will be the strongest country in the future so Mandarin must be the global language in the world instead of English, I still believe that the future status of English as the global language is assured.
There are some reasons people think English will not be the global language. First, English is difficult to learn because the words change frequently. Second, except English-speaking countries, most people in the world don’t speak English in their daily life which means English is not used. Last, because of the economy of China is growing now, people think Mandarin (Chinese) will replace English and become the world language in the future. However, the change in English is in words not in grammar. Also, there are rules for word changing. As following these rules, it is not a big deal to learn English. Moreover, although most of the population of the world does not speak English, it is still considered as the common language which people can only communicate with when they speak different languages. Furthermore, it may be true that China will be the strongest country after and Mandarin will become an important language, but Mandarin will probably only become one of the global languages instead of replacing English as the global language.
Therefore, in my opinion, I agree with the future status of English as the global language is assured. Many people keep learning English because they consider English as the global language as well.