Hulk has changed a lot in the last 5 years, some good, some downright retarded like Spaceship Hulk, and his durability isn't what it used to be. He can be killed, and most likely permanently this time as the Green Doors in Immortal Hulk don't work anymore.

Until someone else decides to change the rules in a new run which is the MO with most writers to ignore what came before or just make shit up for their own pet projects that can be retconned away further down the line if it ends up being too retarded or if the new writer just doesn't give a shit about continuity.

Edit: Also this,

Hulk can survive in space

Doesn't help much because he's then just floating aimlessly through space. Superman and similar characters can still fly in space. Hulk can't thunderclap his way through the empty void of space precisely because it's an empty void.

Hulk has changed a lot in the last 5 years, some good, some downright retarded like Spaceship Hulk, and his durability isn't what it used to be. He can be killed, and most likely permanently this time as the Green Doors in Immortal Hulk don't work anymore.

Until someone else decides to change the rules in a new run which is the MO with most writers to ignore what came before or just make shit up for their own pet projects that can be retconned away further down the line if it ends up being too retarded or if the new writer just doesn't give a shit about continuity.