The opt-out line is a legal requirement with a local flavour. What satisfies CAN-SPAM reads wrong to a German recipient under GDPR, and a formal statutory sentence at the end of a deliberately casual email is jarring.
Each campaign can now carry its own unsubscribe clause template. Write one for your EU campaigns, another for US ones, another for the audience you address informally — the correct one is appended to every message that campaign sends.
The unsubscribe link itself keeps working the same way, including one-click opt-out headers.