Two things matter: (1) Content (2) Accessibility to the content.
For (1), we need more active participations and generate more content.
For (2), the mechansim of remote community discovery and subscription are still very tedious and error prone. Not only the remote community is not visible to the instance (Yes I know it's lazy fetching but it still does not work somehow for some remote community subscriptions), but also the lack of integration of community browser are still hard for general users.
In the last few days I have spent countless hours to try community subscriptions on a number of instances.