We don't even know what the injury is yet ... so premature to talk about anything until the MRI is completed and results known.
The Warriors will get a week off before the next series starts + a likely 2 week series against the Clippers before playing the Spurs. If it is just sprained knee ligaments then it's very possible that the Warriors will get Curry back.
And, while unquestionably Curry is the best player on the team and the league, they have many other pieces on their roster that are able to play at a high level. While you'd have to put the Spurs as the favorites at that point, I don't think you can write off a team as talented and proud as the Warriors. They'll figure out something.
If Curry's less than 100% for the San Antonio series it will be a bloodbath.
San Antonio is damn near as good as GS with Curry at full strength. If he's at 81% GS will be lucky to win two games. If he's out it's probably a sweep.
San Antonio is a monster.