Even if India's per capita GDP has largely caught up, there'd still be a substantial underclass of young workers who are likely to be attracted by higher income

Even if India's per capita GDP has largely caught up, there'd still be a substantial underclass of young workers who are likely to be attracted by higher incomes they could get in China, given the differences in income distribution. And migrants nearly always sacrifice a certain amount of democratic franchise just by virtue of not living in a country where they have citizenship - it doesn't seem to be a great deterrent, compared to other cultural/language barriers and having to live far from family etc.