From a number of queues standpoint, there's no risk, and it's one of the shiny features of RabbitMQ!
The only caveat is around the accumulation of pending messages, if/when the answers are not consumed (but that's not specific to RPC patterns, nor even to RabbitMQ, but a thing you have to deal with in any pub/sub systems: unread messages accumulating, and dead-letters). This is just a reminder to set TTL policies ;-)
I highly recommend you the 'RabbitMQ in depth' from Manning. As for as I know, it's the best resource you could find about RabbitMQ, and has a complete chapter on performance (chap 4), scaling (chap 7), and also RPC samples using the message-id and correlation-id built-in properties (Chap 6.1)
The whole book is worth the read if you're using RabbitMQ. But with Manning livebook's tokens, you can also just unlock a few paragraphs for a few tokens (with the first 500 ones you got with an account, you might read those part for free)
The book homepage: manning.com/books/rabbitmq-in-depth