The only thing that makes me sad is that I come in the morning now and there is a handful of posts instead of tons because everyone is chatting instead of posting! Not to mention the in jokes and all that but that can't be helped.
I think you raise valid concerns but, to be fair, I think the drop off in posts is more to do with shiny wearing off and not entirely the chat. The handful of posts is not that far off from what I'd wake up to for stretches at a time on 3.0 and then everyone was trying to remind me it is a cyclical thing.
To also be fair, the chat itself has experienced a rather sharp decline in active users (I think, anyway) since it was first installed.
I think everything will balance out with all that.