The middle path is limiting (not ending) migration while actually trying to help these counties (in particular victims of one’s past colonial ambitions) through aid, investment, and free/subsidised education for their youth.
I say this as a someone who immigrated from a dangerous country to the first world.
The only way the current plan even approaches sustainability is if the brain drain on source nations is sufficient to keep them stuck and suffering. That should make it very clear that the humanitarian impact is a side effect and not the goal.
Selecting "the best people" is the often-overlooked step. A lot of countries just want to import cheap labor and get easy economic growth today, damned be the consequences.
I don't have enough cruelty in me to demand that someone should stay in Sudan and try to "fix" what's happening there.