There is no public roadmap (neither features nor release dates) available.
Regarding release dates:
"It's done when it's done" and I personally like that mentality since I think it does not help admins/users when they release half baked stuff with bugs etc. So it's taking as long as it needs ;)
Regarding features:
You can get a good intention of upcoming features by searching for the crumbs of the moderators and admins here in the forum, taking a look at the github repo of osTicket (e.g. pull requests and especially the develop-next branch).