Communities and retention sound like a perfect match.
But they’re not.
The quality of the product, competitors, price, the reputation of the brand, reviews, other promotional channels, other loyalty schemes all usually have a greater influence on retention than a community.
I’m sure you can point out exceptions, but be aware those are the exceptions.
Most communities with retention/loyalty-based goals from five years ago are gone today. They’ve moved to social media channels, closed down, and laid off their staff.
Instead of loyalty, I’d focus on customer acquisition, gaining powerful insights, saving time and money, reducing costs. A community has far more power and influence here.