This is interesting.
You idea popped as I was wondering whether to add the Home Place designation to GEPS 043: Improving GEDCOM support for Places.
And noticed that while there is a proposal to add a UUID data element to the Gramps People model, there isn’t a similar UUID extension for the Place or Citation model. However, the existence of a UUID for People seems like a 1st step towards a harmonization/merge engine for Gramps.
I’ve begun using the GeoNames (wiki: Geonames; addon: GeoName, PlaceCleanup, GetGov)
PlaceCleanup highjacks the Gramps PlaceID as a UUID. That is OK if I will only use the GeoNames gazetteer. But what happens if someone writes a plugin that leverages features an external database like PostGIS or SpatiaLite in the future? And such plugins might scrape data into Gramps (like PlaceCleanup) or become more sophisticated (like @StoltHD suggests) and poll for live updates.
So how about UUIDs for the Core Objects in Gramps? Hopefully with more than a Name and Value tuple.