With the introduction of IndexManager in version 4.0 we can now delegate index writes and updates to an external engine.

We still require exposing an IndexReader to the query engine, it would be nice if we could delegate the query execution as well to a remote engine like Solr or ElasticSearch (not thinking about anything not Lucene oriented).

This would also require a way to properly remote the Lucene Query, and likely a way to export our mapping to the alternative indexing engine (for example analyzer definitions and field storage options)

I described some ideas on the forum:
https://forum.hibernate.org/viewtopic.php?f=9&t=1023888