There's quite a bit new in the coming BizTalk Server release. In CTP1, testers get support for Windows Server 2016 and SQL Server 2016 -- both of which are still in preview themselves. Windows Server 2016, the fifth technology preview of which is due soon, is expected to be generally available in Q3 2016, SQL Server 2016, currently in its fourth and final public release candidate state, is likely to be released to manufacturing very soon.
BizTalk Server 2016 also adds support for Office 2016 and Visual Studio 2015. BizTalk Server Azure virtual machines are fully supported for production environments with this release. SHA-2 has functions are supported, as well.
Microsoft also simultaneously made available CTP1 of its related Host Integration Server product. Host Integration Server 2016 adds support for BizTalk Server 2016, Windows Server 2016, SQL Server 2016 and Windows 10.
According to Microsoft's documentation, both BizTalk 2016 and HIS 2016 will be generally available this Fall. At this point, it seems these products are on track, as Microsoft's integration roadmap from last year indicated BizTalk 2016 would be out in the fourth calendar quarter of 2016.