Intel stagnated and at the same time started implementing some rather anti-consumer practices. This allowed AMD to take the performance lead off them with their latest generation of products. It’s fantastic that the market for processors is so competitive. I’ve grown to not like Intel very much recently, but I’m glad they’re here. They’ll keep the pressure on for further innovation, so AMD will either need to keep up or be overtaken again. Either of which is a good outcome for consumers.

They don't need to die, but if they don't begin to compete they simple will die.

Resource allocation.

Intel dying would free up resources for development by other companies.