It seems to me that things like subscriptions, could be ubiquitous through the oxwall core. I will give that some more thought, before posting on uservoice.
I am going to give this a shot. Should be done before the 16th of this month. It might be a plugin (I hope that is doable) or otherwise my developer will rewrite the blog plugin and embed that. Will be updated soon.
Unfortunately my developer hasn't been able to finish the modification / plugin on time. I am now trying to find out what is going on. For now this has been postponed to an unknown date - not canceled. To be continued...
I have made this plugin, just uploaded to the store and waiting to be approved. Once it is approved, I will post a link to it and you can mark this as solved.