Will there be an Update/DLC that opens the Rest of the Starsystems ?
Or will there only be Saisons until EoL of the Game
He and the rest of his Team is holding their Cards close to the Chest for now. With some time one by one those Keys shall be opened to other Systems and Planets and surely to other Races not introduced yet. I´m sure of it. Why else would there be Star Systems with locked key on them?! Surely it will come.
By 3rd Season as he say they work on now, I´m sure we will see something really nice coming along. But what I also do hope to see coming along with that is in fact new Troops Choices/Warriors for the different Races already out. If you take a look in their Codexes if you play Warhammer, you´ll see there are quite a few Choices they have not implemented yet in this game.
New star systems and DLCs are not in the preparation though but this is still an open issue, we haven't yet discarded the possibility to add fresh story contents to Inquisitor either.