Economics of Re-migration?

Hey, a german here. As a lot of you may know our largest growing party is a right wing populist party that talks of re-migration. Now other conservatives are starting to talk of it too. So I was wondering how bad the impact is going to be, should they implement the policy anyways. (For the record, I'm not for these policies, I'm just worried and a Pessimist…)

My hope is that they will try and get more natives to have kids again and that we'll have a rocky period for two decades or so, until more people have been born and raised I guess. Again, I really have no idea and just hope for the best.

Please keep it respectful in here I just want a longterm Assessment, not a racewar in the replies…