I agree, there is still no such ability in Oracle RDBMS. However, that is easy to do:
1. You can disable the foreign key constraints in all the child tables and update the PK value. Then update all child tables to reflect this new value. Now re-enable the FK constraints in all child tables.
2. If you define the FK constraints in the child tables as INITIALLY DEFERRED, you can straight away update the PK value and all child tables in one transaction.