Agreed.No. Since Hulk can breath underwater, he'd survive a Noah's-ark scenario, but not actual obliteration where the planet pops into space dust like Krypton. He'd be floating out in space for a while, alive and well, but sooner or later he'd need to breathe.
If anyone bothers to "fight" him before he suffocates(they probably have a window of a few to several hours), they get massacred. The exceptions, however, are pretty big. People a floating World Breaker couldn't deal with are;
Anyone that can, of course, survive in space indefinitely or BFR themselves to a safe place after doing what they want with Hulk
Anyone that CAN'T survive indefinitely in space, CAN BFR themselves, but have no sense of self-preservation
(previous two are prerequisites)
Anyone that can fly really fast
Anyone that can project attacks of decent force
Anyone that can use powers that can manipulate objects from a distance, like telekinesis or a GL ring.
That said, there's the simple possibility of a thunder clap, which from World Breaker, would do quite a lot of damage in space. And anyone that actually approaches World Breaker gets massacred.
Besides that, I don't see why GL couldn't just nudge World Breaker off into the sun. In space, Hulk's got almost zero defense barring thunder clap and anything in arms reach.
I'm not saying World Breaker can beat "anybody". On an indestructible world, lots of people could contend. But we're talking about Earth. So let's face it, he's World Breaker. He could barely control his own power, so much so he couldn't even walk, much less actually "fight" anyone. So if World Breaker were put on any planet with the stip that he is uber-enraged and INTENDS to fight, global damage is as instant as a hearty stomp. And, in my opinion, the best way to win a fight is to destroy the whole damn planet. What's left hardly matters. So, technically, the DC Hero leftovers win, but then they have to find a new home.