Hey Glenn,
Thanks for reaching out. We have RSS feeds by default—if your site’s calendar is example.com/events, then example.com/events/feed is an RSS feed.
“Custom” feeds are not supported at this time. And while there is no plan to enable custom feeds at this time, yes, when the JSON REST API finally arrives in WordPress Core, we will be supporting a JSON feed of events too.
I do not know when that will be because the inclusion date of the REST API in Core is still not defined yet. But when WordPress Core supports it, we will too. 🙂
Cheers,
George