I can't say I've seen many people claim it's a "Zelda killer" (they're barley even directly competing right now, so it'd be odd to say either is a "killer" of the other), but i'd be shocked if we didn't see a sequel in some capacity. It's one of Sony's fastest ever selling games, despite being an entirely new IP. They were happy to keep the Killzone series (GG's last IP) going with it hitting 2 - 3 million LT sales per entry, i expect they'll also be interested in continue a series that managed those numbers in 2 weeks :p