On the occasion of the recent death of a pop-singing character, many Ulama said that he might have died a Muslim.

Answer

The 'many ulama' to whom you have referred are dunces gorging out bunkum. Any of the millions of non-Muslims dying daily on earth may have died as Muslims. Allah Ta'ala Alone knows. While we have no information on the character's elder brother, we do know that numerous poverty-stricken persons in squatter camps, people dressed in rags do embrace Islam quite frequently. They are of concern to us, not some notorious character whose life and after life are conspicuously displayed with kufr. The Shariah is our criterion, not what the condition of a man after having crossed the threshold of this earthly abode on his way to either Illiyyeen or Sijeen – Jannat or Jahannum. That is Allah's exclusive preserve.