그래서 다음은 뭐가? "그래서" means "so" "다음은" means "next" (다음 is the rootword) "뭐가" means "what" **you can change mwoga (뭐가) into other word for "what" like "뭐지" or "뭐니" or "무슨 입니까 (formal)"

'그래서, 다음은 뭐냐?' is correct - if that phrase is used to be sarcastic to someone. But, in daily conversation, we use '그래서 뭐?' - which means 'So what?'