We are currently using it for development, however the last release was Service Bus 1.1 over two years ago.
Should Service Bus for Windows Server be avoided?
Edit: It is officially dead. Microsoft "will not provide an immediate successor for the standalone Service Bus for Windows Server 1.1 product" and it "and will go out of mainstream support on January 9, 2018".
You may want to monitor this Stack Overflow Question (which points to this UserVoice idea) for updates on it being brought to Azure Stack so it can be used on-premise. The latest update from Microsoft was from Sept. 30, 2018 - "Thanks for your feedback. We are pleased to inform you that we are bringing Event Hubs to Azure Stack. We announced Private Preview at Ignite 2018... Service Bus will follow next." As of Dec 2019, Event Hubs is still listed as "IN DEVELOPMENT" on the Azure Stack key capabilities site.
Original answer (Aug 4 '16):
The short answer: Service Bus for Windows Server does have a future as part of Azure Stack but it is not going to be free and will not happen this year (2016).
Apparently the roadmap was announced on May 12 at Integrate 2016 during Clemens Vasters's Service Bus – Roadmap, What’s next? talk. You can listen to the announcements related to Service Bus at about 40:35.
Interesting quotes from the video:
Thanks to user Arunkumar BizTalk360 for pointing us in the right direction in this Microsoft Azure thread