Drew DeVault has already written about how Elastic's move is an affront to the contributors to the ecosystem, including myself. To say I am disappointed would be an understatement.
This license change does nothing to stop Amazon from using the search product, which they will obviously continue to do, and as is their right under the previous license.
What it really does is makes it so free software projects like my own cannot use your product, ever, because my software prohibits linking to software like yours. I cannot use your search library under its current license, which means I will have to either use an old version or find an alternative.
Elasticsearch is a technical marvel, a testament to the free software community, and it rightfully belongs to its contributors, not to Elastic. I will throw my weight behind any surviving fork. Shame on you, Elastic.