This sounds like a feature request ;). I would submit this to github (https://github.com/elastic/kibana/issues/new), with some context and added explanation to how you would like to see Kibana use other datasources.
That said, I am not sure if there were ever any. A lot of Kibana's core functionality is very tied to Elasticsearch. For example, Sense/Dev Tools to write ES queries, or the visualizations which tie into the aggregations API, etc...
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