Define "good." The people immigrating aren't suddenly going to behave like Swedes - we've seen that. Will the geographic entity that is Sweden maintain or grow the population? Sure. Will it still be Sweden? No. If the majority of people are from, say, the middle east, it'll be run like a country there. I don't think that'll be good for the existing Swedes.

If you could somehow pick the best and brightest from those regions to immigrate - sure, great, probably good for your country. Existing countries are the way they are because of their people. When you shift your demographics to such a degree, your country will also become that. I don't know why this is such a hard concept for people to grasp. It's the same base concept that explains why the US policy in the middle east has failed so badly over decades. The people there largely don't want US-style democracy. Some do, sure, but the majority either don't care or like the system they have.