The WiX v3.10 release candidate 2 was released today. As you know, Bob drives the v3.x releases so, as you'd expect, he has a more detail about the second release candidate. Barring any issues this will be the final release candidate of WiX v3.10 so official Visual Studio 2015 support is imminent. That also means this is your last chance to verify that we haven't broken something important. If we did, please file a bug.
Something I'll be talking about more (probably on the FireGiant blog) is the support for ISO/IEC 19770-2:2015 (aka: SWID Tags rev2). We see some interesting possibilities going forward.
In the meantime, keep coding. You know I am.