Starcraft 2 is at its twilight.
The biggest leagues of South Korea have disbanded. [1] The prolific progamers who transitioned to Starcraft 2 have gone back to Broodwar. [2]
Blizzard itself has scrubbed all references to Starcraft 2 on the very home page of Starcraft. [3] Except for the twitter embed, it has only only one "2" character... in the copyright statement.
My take is that the future for the Starcraft franchise will be through remastered and potential expansion packs following it.
Starcraft 2 had a good run but, with the entire RTS genre stagnating [4], I don't think Blizzard wants to bet on anything less than the top horse.
[1] https://www.kotaku.com.au/2016/10/the-end-of-an-era-for-star...
[2] http://www.espn.com/esports/story/_/id/18935988/starcraft-br...
[4]http://www.pcgamer.com/the-decline-evolution-and-future-of-t... (Aside from MOBAs)