I called them abstract but better term would be templates. This term is already used for entities that are based on templates but I mean templates for entities. It could be something like lightweight integrations.
How I would see it:
abstract:
mylight:
light:
platform: mqtt
unique_id: "mylight_{{some_id}}"
object_id: "mylight_{{some_id}}"
name: "{{name}}"
state_topic: "my/topic/{{some_id}}"
command_topic: "my/topic/{{some_id}}/cmd"
payload_on: "1"
payload_off: "0"
mylight:
light:
- some_id: "101"
name: "Kitchen Light"
- some_id: "102"
name: "Bedroom Light"
Something like this would be great both for entities and also for cards as well. It would greatly simplify large smart homes. Currently there is a lot of repetition required or need for a custom integration.