I think thebluefeline meant that issue 25 will be Soy's last issue, not the last issue of the series.
Awww I really loved how well his style meshed with this team. Sad to see him go but I hope he does well after this too, he's got a distinct style that matches comics but still has his own signature all over and theres very little I can think of that won't suit his art.
Oh no... That's a terrible news (especially when I'm anxious about the reveal of the letters tommorow). He won't be drawing future stories rooted in those letters... Part of me was also expecting his own Red Hood design could show up in comic or games one day