What downside exists for Elastic from making this change? If AWS makes valuable contributions on their fork, Elastic will absorb them, but the converse is no longer true. If the downside is that the AWS hosted ElasticSearch service will become successful, well, that was happening anyway before the relicensing.
I don’t see a path for absorbing and relicense. Especially if the core code method signature diverges in the future. It is going to be a lot of trouble for Elastic to absorb non-trivial contributions from the fork.
