The current way GeoNames manages past names cannot answer historical questions like "where Constantinople was ?" or "when was Stalingrad renamed Volgograd ?"
I propose to date geonames, by adding to any geoname the time interval (start date, end date) when that name has been used. This additional information should be optional (likely absent for most geonames).
Geonames will be searched by both the spatial and temporal cohordinates.
It is a great idea. In fact I am just returning from a workshop for the DIGMAP project in Lisbon. Among other things adding dates to alternate names was a main topic of discussion.
Do you have a dataset we could start with and populate the dates?
But I can investigate. For instance, the company where I work partecipated to a project in which some historical italian toponyms are managed. Maybe part of those data are publicly available.
I will also search internet for public databases, like the following: