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.

This presupposes many things which are not reasonable to suppose. Like these immigrants being economically useful instead of fiscally negative their whole lives, or that people are just interchangeable economic units and forcing together separate groups will not cause any trouble.

Immigration is not a solution to low fertility. It might be a solution to labor being expensive, particularly if you’re a capitalist, but it doesn’t solve the problem of low fertility among a native population.

This might sound facetious but I'm completely serious -- why does this "problem" need a solution, and especially this solution? If the Swedes have collectively decided they want less fertility, who's to judge them?

A country is not just a random set of people. They have to be linked by a common set of values. Importing people who don't want to assimilate, or importing more people that can be assimilated will lead to disaster in the long term.

Additionally, immigration is not a solution for low fertility. If they assimilate, they will also have a lower fertility rate, pushing the problem down the line. If they don't assimilate, and keep a high fertility rate, they will replace the population.

Immigration is a positive thing, but it needs to be low and open only to like minded people.

Robots are also advancing fast. They have all the upsides and none of the downsides of mass migration.