I've been thinking about entities recently in the context of my use and have had a look at the preview. It's a super exciting feature I can see many applications for.
For an entity, could/would the dataset contain duplicates for a given entity ID, in essence recording the history of that entity (eg tree circumference at a number of historical visits, weight at different ages etc). The most recent entity could be pulled by other forms based on timestamp of creation or a 'current' type flag, and a dataset could be pulled with the history for a field(s). Or is this the intent of archiving an entity so you have one live current state, and many archived (but still able to be consumed by a form or queried externally) states?
The datasets are CSVs currently, is there any way an entity could include media of any sort, eg a drawing/photo? add files exists as 0.09. Before it's added, could the dataset have an image field that would trigger Central to add those files as attachments?
Creating multiple entities from a single submission (also discussed here) isn't on the functionality sheet yet, but seems to me to be quite important. eg for a family, add details for each member via a repeat, and add all members to the dataset.