I don't know, I figured the ring would be smart enough to know punching Kronalax into the sun would kill him. But if your right Krona might still come back. The next movie will need to make clear if lethal force is a no-no still. And I'm pretty sure Paralax isn't dead. Krona got the yellow light and his head became huge, Hammond got the yellow light and his head got big. Sinestro got a yellow ring, so I'm guessing he won't mutate or whatever but may have Paralax influencing him. I'm thinking anyone using the yellow rings will have Paralax influencing them to a degree.