Enticing subject I hope.
Here's my thought. I've got servers with 256GB RAM. The optimal heap size for an ES JVM is 32GB (or just under that). How cool would it be if there was something like a "data-shared data node" (TM) that could run on the same server as my "regular" data node, but NOT need it's own copy of the shard data on disk? It would instead refer to the data already there from the "regular" data node.
This data-shared data node could use its entire heap for queries alone, and query off the data that is "owned" by the "regular" data node. I could run 1 regular and 2 shared JVMs per server, and dramatically increase my query potential without having to create new copies of the data!
That would make my day.