Copper wiring can last up until 100 years++. The copper itself is not the issue but the cabble sheath. If u are using good quality cable with correct spec, it can easily last up until 70 years++. Should you rewiring your whole house?depend on budget and safety

If ur house is a 2 storeys house, it is more convenient to have 2 DB. Easily to troubleshoot and if got any issue, the wiring route should be more shorter hence cheaper