Song during Heart of the Swarm Ending Cinematic

It's called Ascension by composer Neal Acree, featuring The Skywalker Symphony and Chorus, and vocalist Laurie Ann Haus.

Neal Acree has released the full track on his Youtube page:

I stumbled upon this a few days ago. I hope you're still around to enjoy it!

It is Ascension by Neal Acree (SoundCloud).