No. Those places will still be breeding grounds to feed back into western nations in the form of immigration.
Nature abhors a vacuum; even if it's based on population.
Your solutions are as follows:
A-, Conquer dictatorships around the world and attempt to foster democracy with a functioning rule of law.
B-, Build a wall with sentry guns to keep them on the other side.
C-, Genocide via nuclear or biological.
'C' is pure evil. Effective yes, but evil!! 'B', can work, that only so long as there isn't a revolution or radical change in prior governance. Considered short-term in the span of a few generations at best. 'A' is the best long-term solutions, but also the most difficult as it takes influencing and changing the culture of a "western" mindset adoption.