I have lost faith as well, but in my case it might just be that Elastic are working on too many integrations, or that Rails is just not a priority for them, but the official elasticsearch-rails gem is set to support ES6.0 by Q2 or Q3 in 2018[0], remember that Elasticsearch 6.0 was released November, 2017.

[0] https://github.com/elastic/elasticsearch-rails/issues/756