The core work is done, yes, draft-ietf-jmap-core-17 and draft-ietf-jmap-mail-16 [edit: fixed draft name] are in the RFC editor's queue, how long it takes to get through that queue can depend on a lot of variables. At the end it goes to "AUTH48" which is notionally 48 hours long but a few weeks is more likely in practice, and then it gets cut a number and becomes an RFC.

The Working Group still has open items, including calendaring (because people never can build a mail system that doesn't involve calendaring for some reason), handling "read receipt" type features and because this is Current Year a mechanism to involve WebSockets. Either those will eventually also be polished into standards, or they'll be abandoned at some point and undelivered.