One difference between India and most other poor countries is that in India, problems are admitted and talked about openly. They are working to control this problem, and they probably will make some headway.
My impression is that in the U.S., sex selection tends to be for girls. In both countries, it is very wrong.
For China, the excess males will result in internal civil war, or external adventures.
This could be a Chinese tyrant's slogan in a time of economic depression and social problems from too many males:
Conquer them! Kill their men, take their women, colonize their lands!
That call could send tens of millions of wifeless childless landless Chinese abroad with a rifle in their hands.
I would not feel secure in Taiwan, the Philippines, Viet Nam, Malaysia, etc. with China looming over....
Or a de-populating Africa for that matter.