According to Hishamuddin, Malaysia lost 47,769 citizens due to emigration between 2002 to 2012. Of these, 40,624 ended as Singaporeans. In the same period Malaysia received 74,092 applications to be PRs. Thus Malaysia will have a net gain, so nothing to worry about.
This is quite similar to the Singapore situation. Though more Singaporeans are migrating, to cash out or because of their children’s education, many many more foreign talents are queuing up to replace them. Singapore will end up as the net gainer with more talented foreigners coming in to replace the lesser talented Sinkies that left. Singapore must be very happy with this state of affair, a very fair exchange in its favour.
Think Malaysia too will be gaining more foreign talents to replace their unhappy and not so talented citizens that have chosen to move out since they could not make it there. It is a win win situation really. The two countries got to get rid of the people they did not want and got in return talents that they want. And those who left are happier and those who came are even happier.