When Princess Celestia visited Sunset Shimmer, her former student was now feeling so horrible about her past and begged for Celestia’s forgiveness and tried to apologise for her spoiled and bad behaviour. Celestia told her that she was so proud of Sunset’s reformed self and for having that chance to start over.

Celestia wanted to give her a most precious gift, a choice. That she can return to Equestria with her, or she could stay behind and create more of the magic of friendship, but now Sunset had a better idea. Which is having both the human world and Equestria combined together with Canterlot High School and Crystal Prep now in Equestria and all of the ponies, the humans, including all of the pony and human counterparts living together in perfect harmony.

Sunset Shimmer: Now we can all be together.

“Time for a Musical Number”

[Spike:] I hear the music playing

It’s swinging and it’s swaying

A little rhapsody

Today we’re so delighted

Today we’re all united

Both human and pony

I see pegasai flying

Even the dolphins diving

We’re trotting fancy-free

We’re feeling better now

We sing together now

Both human and Pony

La dee da, we got the beat

Move your hooves and move your feet

Life is sweet, life is grand

Blowing flowers with the bass brass brand

[Princess Twilight:] There’s no more stormy weather

[Sunset Shimmer:] Now we can sing together

[Sunset and Twilight:] In perfect harmony

We’re feeling better now

We sing together now

Both human and pony

[Spike:] Those humans sing

Those ponies sing

Life is sweet as sweet can be

Both human and pony

[All:] We’re feeling better now

We sing together now

Both human and pony

That song is an inspiration from “Here on the Land and Sea”