Genuine question: what is it that you need from Kafka partitioning?
Not OP, but what I need from Kafka partitioning is guaranteed message ordering (per partition key).
I don't know about RabbitMQ, but with Apache AMQ there is message grouping, which is kind of similar, but not quite the same. With Kafka it's unavoidable, which is good.
Getting insights into the roadmap for this would certainly be interesting...
[1]: https://github.com/rabbitmq/rabbitmq-server/blob/v3.9.x/deps...