If I were to speculate, without any useful information about what comes after this year’s last update, there will be some kind of update in the spring of 2018 which will have at least some compelling feature-function. I base this purely on the idea that Steinberg released Dorico 1.0 in October of 2016, and from a financial model, Steinberg’s renewing products in the $400-$600 range typical see an update every 18 months (or sooner to) see a cash infusion into the expense pipeline for the product. Given that they will have gone for more than a year without a substantial cash infusion from the product base, I think they will be pretty anxious to see some renewed revenue; however, to assure that people actually purchase the update, there will need to be something reasonably important to assure the majority of the base purchases the update.
There are certainly several technical/functional avenues to make this update happen in the spring-summer timeframe. Plugin language, more extensive composition tools, more extensive graphics/glyph editing, real-time midi transcription, improved DAW exchange, playback improvements, sound library improvements, Noteperformer support, and the like. Any of these could justify at least a modest ($60-$80) upgrade fee and several at once might justify $100 or more.
More far-out stuff like handwriting/pen transcription (a la Staffpad), ipad tools, or cloud sharing is probably not in the center path as they have made little indication they are pursuing these avenues.
For myself, I’ll just keep following along with Daniel’s blog and what interviews he gives this winter. The future will reveal itself soon enough.