Pakistan Defence

Do Southies view regional immigration from Northern states as a threat to their identity and culture

Not as a threat to identity and culture but jobs; practically all low end jobs are done by biharis, UP, Orrisa and rajastan people.
But considering how these hindi speakers nearly halved the numbers of punjabi speakers, i guess they are a threat to culture too.

Interesting my concern is uncontrollable birth rate India has not just for Asia but the world yes Africa has more growth China harnessed theirs for economic development what's India goal for population or they just siphoning them off for cheap labor abroad

Yup, its scary, tbh. I mean there's babies everywhere.
I guess the same situation applies to Pakistan as the birthrate there seems pretty high too.
Rather than govt. forcing us, people should consciously try to understand the situation and aim to improve Q of life with perhaps 2 babies instead of half dozen.