The Master Chief and passing the torch

In the end of Halo 4 we get to see through the eyes of John right before he triggers a nuke. In that moment he looks up to see Earth and almost instantly sets the bomb off. He did not ponder long over setting it off, could this be a sign of selflessness?

In Halo escalation he talks of dying on the battlefield while having his helmet crushed by the Didact. A fate he always knew would await him.

The Halo 5 ad featuring Chief has him laying down, defeated in Locke’s trailer.

You win some you lose some, Chief has won most battles, yet he has lost everything.

Is the Chief ready to accept his fate and die?