Azure search and Lucene Search
Azure Search is Microsoft's response to providing a cloud based indexer. It uses Elastic Search as the underlying driver, but the Elastic Search engine is not directly accessible. Currently Azure Search is only accessible using RESTful Web services or the Azure Resource Manager control panel.
Switching from SOLR to Azure Search
As for the Sitecore provider, it will hook into Sitecore in a similar fashion to Solr and utilize all of the same Sitecore ContentSearch api.
My initial thoughts are that it's possibly viable so long as all of your Sitecore roles are in Azure and in the same Resource group as well as same virtual network.
Any other use or connection and the latency makes indexing so slow that it's not recommended. To give you an idea, it took approximately 9 minutes to index 1000 items from local laptop to Azure Search.
For a full cloud implementation though it is very promising.
Jamie Scott (Slalom) wrote one of the original implementations that works with Sitecore 8.1. You can find his Github repo here: Sitecore Azure Search Provider for Sitecore 8.1. rel="noopener noreferrer" Here is a link to the LinkedIn Blog post he wrote about it.
Azure Search Core Concepts to Patch Per Environment?
Azure Search uses indexes as the primary collection. If you need to use different indexes for a different environment you can setup a different service connection.
Also adding that there has been pretty significant comparison research done between native Solr and native rel="noopener noreferrer" ElasticSearch. You can find rel="noopener noreferrer" that comparison here: solr-vs-elasticsearch.com This research is not inclusive of Azure Search, but more for educational benefit if nothing else.