Conversions are largely superficial stamps. Most people get converted for purely outer reasons, monetary and otherwise. Such people do not belong to any dharma. Whatever they may profess, their true dharma is money. Whichever God or gods they may worship, their true allegiance is to the god of ambition and politics. They may belong to Christianity or Islam or Hinduism but they are actually the followers of Adharma. Such people are like chameleons, opportunists by nature and their numbers in any religion is simply like the multiplication of weeds in a field whose value lies in its capacity to do harm. Whether they remain a Hindu or get converted they stand in the way of the manifestation of Truth and Light. It is better that they go so that one always knows the true from the false.
The real followers of Sanatan Dharma have always been few because Sanatan Dharma is not about numbers but quality. Its aim is to build humanity in the image of God and whoever engages with this process of spiritual evolution is a follower of Sanatan Dharma regardless of his name and nationality. No amount of artificial lights can compare with a single sun.