Major Description
Currently htrace-zipkin writes to the Scribe Thrift endpoint. However, Scribe is pretty much dead (although this is just Thrift interface so doesn't really need Scribe).
A Kafka receiver would likely be useful not only for htrace-zipkin, so I think it could live outside. The htrace-native would be harder to get working with Kafka as there no supported Kafka native client (perhaps this could be experimented with https://github.com/edenhill/librdkafka).
Writing to Kafka would also be possible by having a service that translates from Scribe Thrift to Kafka messages, however it would be nice to get the Kafka producer semantics on the client side (e.g. sync, async, batch size, etc.). This will come at the cost of having the Kafka producer as a dependency (larger jar), though as well as have a more complex receiver (multiple threads from the Kafka producer).