Of course there will be "brain drain" as long as we leave everything in the hands of the DRDOs and HALs. For the country's defence industry to progress, we need to urgently free defence manufacturing from the clutches of the HALs and NALs and DRDOs, otherwise we are doomed.
In the 1990s and earlier, there was a "brain drain" in every field in India. All the IT wallahs who work in Bangalore, Hyderabad, Pune, etc. would have simply emigrated to the West, and those who couldn't would have taken up a job as clerks in some PSU or the other. Now, at least so many Indians have got a job in India, preventing brain drain and fueling a massive boom in the Indian domestic economy.
Until something similar happens in the defence manufacturing industry, we are condemned to suffer ineptness of the DRDOs and HALs and NALs and other sundry PSUs. All this silly emotional rhetoric of "serving the motherland" is not going to achieve anything. Until private players are allowed to form a military-industrial complex in India, there is no hope.