MongoDB 3.4 Added support for wire compression through snappy.
MongoDB 3.6 Will likely add support for zlib.
MongoDB 3.6 Will likely add support for a new wire protocol which will not reply with OP_REPLY opcode.

During development of these feature there will be a flag that must be enables to access for example wire protocol compression;

$ MONGODB_36_EXPERIMENT=yes ./configure --enable-snappy

For compression, mongod must be configured with --networkMessageCompressors=snappy