What will happen??
No one will have the BTC address. Hence will them isolated?
In FIAT, people can handover money to someone.. So, i predict BTC will be disappeared gradually.
If a person with BTC and have a sudden death his/her BTC will still be in the network, unless he/she saves all information about his/her btc on notepad and can be easily access by his/her family. Like me all my online password are save on my pc.