What is known for the new game
Blizzard's announcement says STARCRAFT returns to the Koprulu Sector. That establishes the broad setting, not a route, map boundary, playable region, or set of visited worlds.
Blizzard announcement ↗
Setting / established universe
The Koprulu Sector
Blizzard says STARCRAFT returns to the Koprulu Sector. No planets or regions beyond that have been named.
Why the name matters
Blizzard's historical story primer describes human colony ships reaching the distant sector in 2259 and the rise of competing terran political groups, followed by conflict with the protoss and zerg.
This explains the older setting only. It does not confirm which historic worlds or groups appear in the new game.
Blizzard's StarCraft Story Primer ↗Location ledger
Named new-game locations
None announced in the official reveal.
Do not promote Tarsonis, Korhal, Char, Aiur, or any other legacy world as a confirmed location in STARCRAFT. Those names belong to the established universe unless Blizzard directly connects them to this game.