DMK Supremo M Karunanidhi got married thrice. Still, The Former CM managed to keep the entire family united as long as he was alive. Post his demise, The threat of division in DMK due to the rift between Karunanidhi Family Members can't be ruled out.
Karunanidhi had long back announced DMK Working President MK Stalin is his political successor. It was Stalin who kept running the party successfully even when Jayalalithaa hawa continued in Tamil Nadu. Karuna's Elder Alagiri expressed his displeasure over Stalin's domination few times in the past. However, He wasn't able to do much about it as Karunanidhi was supportive of Stalin.
Since 2014, Alagiri wasn't active in DMK and even his loyalists moved to other parties. Karunanidhi sent out Alagiri from DMK for anti-party activities. Family disputes hurt DMK during 2016 Assembly Polls.
After the death of Karunanidhi, Alagiri may become active politically. MK Stalin holds grip on DMK for now but anything can happen in future. Most importantly, Some of the key leaders in DMK are once so close to Alagiri. Those who oppose Stalin might join Alagiri's coterie. Any division in DMK in the next few years leads to defeat in the 2021 Assembly Polls.