Squidex, which supports multi-tenancy, is expected to have varying usage frequencies across teams. User-generated content has a high write rate. I believe we should initially stick with ReplicaSets and ultimately transition to sharding.
There was an old roadmap, but I’m curious why it was discontinued.
I think nobody really asked for that 
… But I am not sure what would be a good shard key. The default shard keys that would make sense are schemas or app, but this would not help you if you would have a super large collection that makes 90% of your whole content.