@ribbitribbitsaga What sovereign country has changed its native language into English as the official language? If some language dies, then it dies because nobody wants to use it. You seem to live in a world where people exist for the languages, I live in a world where languages exist for the people. Forcefully resuscitated languages are nothing but academic curiocities. You mentioned Welsh before, but Wales is not a sovereign nation. Logically Boris Johson would fully support Waxit, after which an independent Wales could make Welsh the only official language. Then we could see how it goes.
I'll leave assimilation to the Borg. If you travel to Country X for a week as a tourist or to do business, why the heck would you want any assimilation? It's enough to know how to behave not to insult the locals accidentally and perhaps know a few words and phrases. If you need to study two years to make a one week trip, you might as well not travel at all.
I don't know about your home country but where I'm coming from, nobody worships the native English speaking countries. I live in a decently patriotic country. However, like you said, it's also a rational country, so it's still within the top 10 non-native English speaking countries, like all the Nordic countries. If English is a highly useful skill, it makes sense to possess that skill. Just like any other necesary skill.