It's worth keeping in mind that we don't always know which projects will truly become successful. The precursor to Elasticsearch, Compass, wasn't hugely popular. When I started looking hard at Elasticsearch, with plans to actually use it, I had to spend a lot of time explaining why I didn't want to use Solr, which was much more popular at the time.
In my opinion, the bottom line is this: if Amazon's exploitative behavior is continues then we're going to see more and more open source products shift towards janky-kind-of-open-source or entirely closed licenses. Small or experimental projects will have open and permissive licenses, their authors will have plans for shifting licenses should the product become really successful.
I think it marks the end of this idea that you could have an open source project and then build a commercial offering around it. No matter who you are, odds are good Amazon will get such an offering off the ground faster and they have a built-in market of AWS customers.
Elasticsearch has made their motives clear: they have real concerns that Amazon is diluting their brand and they feel that Amazon is costing them too many customers with their proprietary AWS product. We can quibble about the morals of Amazon's move (they have none, corporations have no morals) but let's not lose sight of the outcome: Amazon has forced another OSS project to switch to a closed license[0].
[0]: https://techcrunch.com/2019/02/21/redis-labs-changes-its-ope...