Similar to SequenceFiles are Apache Avro's DataFiles. Since these are getting popular as a data format, perhaps it would be useful if fs -text were to add some support for reading it, like it reads SequenceFiles. Should be easy since Avro is already a dependency and provides the required classes.
Of discussion is the output we ought to emit. Avro DataFiles aren't simple as text, nor have they the singular Key-Value pair structure of SequenceFiles. They usually contain a set of fields defined as a record, and the usual text emit, as available from avro-tools via http://avro.apache.org/docs/current/api/java/org/apache/avro/tool/DataFileReadTool.html, is in proper JSON format.
I think we should use the JSON format as the output, rather than a delimited form, for there are many complex structures in Avro and JSON is the easiest and least-work-to-do way to display it (Avro supports json dumping by itself).