It becomes deactivated. Attempt to charge the card at retail counter or online will result in a decline. If the card is linked to any ongoing subscription or automatic payment, the merchant will typically notify the cardholder if they have issue charging the card, prompting the cardholder to provide another valid card.
The credit card account remains active. Only the card itself expires. Any outstanding amount in the credit card account is still due to be paid to the bank.
Cardholder will get a re-issued card before expiry. The card number remains the same, but the validity is extended for another 5 years, and the CVV2 is changed to a new number.
Old deactivated cards should be destroyed to prevent identify theft, by cutting it into pieces with a scissor or a shredder.