Just take the URL from a Youtube video, and paste it in the topic. The video should show up.
Anyway you do make a good point @Chaoswolf210, but what I take from the ending is this:
1. The Didact is not defeated. He may be momentarily out, but from what he's saying, "The Reclamation has only just begun", I'm thinking that he'll return with allot of force behind him to take out the Humans. Like War Sphinxes (possibly shown in the Halo 5 trailer), and other powerful Forerunner technology. Maybe even other Forerunners. I don't think his Prometheans would return seeing that Requiem crashed into a Sun, but anything is possible.
2. I doubt the Didact fused with Master Chief. What I do think is that Master Chief's evolution has been accelerated due to The Librarian unlocking his immunity to Composure, and if you remember correctly, The Composer collects a Human's essence, and turns them into Prometheans. Though this may not be true digitization seeing that the Prometheans are described as both "Inorganic" and "Digitized" in nature, and if it had been true digitization then The Forerunners would have used it the first chance they got.
Anyway about the Master Chief on evolution. The Librarian had to unlock the Composer Immunity for Chief to defeat The Didact. There's no telling what else was unlocked along side the immunity. Forerunner DNA, like you said maybe. Plus The Librarian was on Requiem when it crashed into a Sun, so for more "Thingies" to be unlocked The Librarian would have to be alive... But Forerunners teleport all the time so I think she's fine. To important a Character to kill in the first game she's depicted in, just like the Didact also.
3. Forerunners are not living data. They created the Composers as to turn themselves into data to become immune from the Flood, but The Composer failed, and the Forerunners had to fire the Rings. If they had been data, then they would not had to have fired the Rings to stop the Flood. They would already be immune to them anyway.
Cortana created a Hard Light shield around the Chief to shield him from the Nuke. She manipulated the Hard Light to restrain The Didact momentarily for the Chief to stick a Pulse Grenade to him. She also manifested herself into a physical form using the Hard Light during her last moment with the Chief. I don't think it would have been necessary to digitize The Chief to save him from the explosion.
I do think that maybe Cortana had teleported them both away from the epicenter of the explosion, and then created a Hard Light shield.