Doktor Avalanche
If I were to speculate (badly I'm sure) all the effort is going into the upcoming audio enhancements.
The handful of bug fixes (track view mainly) appear to pave the way for it.
I think that's pretty informed speculation, because it takes into account that doing bug fixes and developing new features are opposing forces. If no one wanted bug fixes, SONAR would have lots of new features and if no one wanted new features, SONAR would have lots of bug fixes.
Historically speaking there's been a flurry of bug fixes after a major version release, followed by diminishing fixes as development ramped up. SONAR 2015 essentially started life as a major version release compared to X3e, and the bug fixes reflect that. The audio changes that have been requested are
major and require a lot of work. Hopefully people will find that the results justify the time required to create those results although of course, there will always be those who will not find it useful for their workflow, and therefore will wish the resources would have been spent elsewhere.
The difference with the new model is that bug fixes won't stop past a certain point as they did in the past, but are ongoing, although possibly at a reduced rate. If development slows down, the team can go back into the "bugs archive" and fix longstanding bugs; there's been evidence of that in the past several releases.
It's important to remember that everything involves tradeoffs. The object is to choose tradeoffs that provide the greatest benefit to the greatest number of people, which requires a bit of science (reading forums and taking surveys) but also some soothsayer chops.