Just wanted to get some advice/input from other Communities.
We're pretty mature by the metrics from Lithium and seem to have hit a plateau with regard to new members - used to be adding 1,000+ a month, now more like 200+. All other metrics indicate a pretty healthy forum but just curious if this is pretty common?
If the decline was gradual and the total number of registered users starts to approach a what you believe to be your total addressable audience then I'd say...maybe.
I'd also have a look at your realease history (did you change something that lead to the decrease?) and monthly active users over time to get some additional context.
Apart from closing in on "registration saturation" for your community target audience as described by @BrianOblingerI can not think of good reasons for a gradual decline. Did you check closely for any steps/jumps in registration completion data that could help you point towards a day?
A big influencer on registration is your SSO integration: It's generally good practice to regularly test your registration and onboarding flow to make sure it's still working as intended. A change outside of community on the SSO flow can sometimes drastically increase / decrease registration conversation rate. Ideally you would review via web analytics your whole registration funnel from the "Register" link entry points via SSO and the various drop out options along that path. Then back to community and through to "Please picka community name" profile completion (if this is enforced on your community).
Beyond registration did your general community participation metrics change? This could hint at some changes to your promotion, e.g. maybe the styling or positioning of community links on your .COM page or corporate emails was changed / removed.
Also how does your registration align with overall business performance (NRU New registered users, MAU? If your overall business is plateauing / decreasing you most likely see that reflected on community.
Any luck with understanding better what happened and why it did with your community metrics, @VF_MikeHales ? Maybe you can also share some of the actions you took to get them moving again. I think we would be even (if not particularly) interested to learn what didn't work and there is probably someone in this community with another tip to share.