Adding the specific trap, because there is now a bulk version of that button and it is much easier to reach than it used to be — you can select every entity at once from the entities list and regenerate the lot from the menu.
What it does not do is update a single thing that refers to them.
- Automations and scripts keep the old string. They do not error. They just stop firing, which you discover days later when a light does not come on.
- Template sensors referencing the old ID return unavailable or unknown, and templates are forgiving enough that a broken one often renders as an empty string rather than a failure.
- Dashboard cards show an entity-not-found tile, which is at least visible.
- Long-term statistics and history are keyed on the entity ID. A rename does not carry the history across; you get a fresh series under the new name and the old one sits there orphaned. Utility meters and anything doing month-on-month comparison are the ones that hurt.
- The recorder database keeps the old rows under the old ID either way.
If you decide to do it anyway, do one device first, then search your whole config directory for the old string before you touch the second one. Not because you will forget an automation, but because you will forget the template sensor inside the automation.
There is community tooling that scans dashboards for entities that no longer exist, which is worth having pointed at your setup before and after any rename — it will not find template references, but it clears the noisiest category fast.