My dream binary format is schema driven, as compact and efficient as Capt Proto or such, but just optionally embeds the entire schema into the message. Then we can write a vim plugin that just opens the file in human readable form without having to fish for the schema. Whenever I am using binary formats, it's because I have a list of millions of objects of the same types. Seems to me that you may as well tack 1KB of schema onto a 2GB message and make it self-describing so everyone's life is easier.
For many web services it would be more often 200 KB of schema (many possible request and responses, some of them complex) tacked onto a less than 1 KB message (brief requests and acknowledgements without significant data inside).