If you’re entertaining visions in your head of player-owned structures or absurd crafting systems, it’s important to note here that “sandbox mode” simply means an option to set up specific practice scenarios. The positive side effect for players at all levels is that you don’t need to wait for a few dozen matches to go just right for you to practice your skill at aiming a skillshot or killing the right targets. It’s a boon for players trying to get better, and while we can’t say it is happening, it’s back on the table for discussion.
League of Legends, Riot Games said no. This made a large number of players very vocally angry and may generally be regarded as a bad move. So when Riot was asked to reconsider based upon player feedback, the answer is a definite yes, meaning that sandbox mode may or may not come to the game but is at least back on the table for discussion again. That’s like a victory.