The main issue you will run into is megatopics, which chat topics always become.
There is a limit of 10k replies for a reason, and you want to minimize the number of megatopics you have as they are very expensive in server (and client) time.
That being said, if you have one of these topics at a time and delete the old ones, you’re probaby fine. This gets into “slow lane” versus “fast lane” discussions and it is something I want to eventually design for.