Shoko (in the ICU) go back to the forth grade and doesn't have her Puberty Syndrome anymore (going back and completing her "Plans for the Future" assignment, which she couldn't the first time). This stops her from being able to time travel (because she wasn't afraid of the future anymore). While everyone retains their memories (Mai wanting the movie part, Sakuta remembering Shoko at the end) from the series and the movie up until that point. Like deja vu/dream; similar to how Nodoka dreamt that Mai died in a car crash.
Everyone still has their Puberty Syndrome struggles which explains how everyone still met each other: Mai, Tomoe. Along with vague feelings from the past timeline which guided them together.
The heart disease situation (which is incurable) would be resolved from a donor and her new found 'will to live' (which has been shown to strengthen you mentally and physically when in a dire situation).
Although it may seem like a weak plot that she miraculously got a donor; the entire series and movie (until Shoko fainted) is another timeline/'Shoko dream world/simulation' which parallels and we meet up again 6 days after Shoko faints in the first timeline/'Shoko dream world/simulation'.
There is no explanation for how she got a donor, but I would like to believe the movie Mai starred in "The Gift of Spring" about a girl with a heart disease waiting for a donor, spread awareness and galvanised people to register as a donor. In effect, saving Shoko's life and giving her a future.
So please, consider registering as a donor, you can help someone else live on. Thank you <3
In order of bawling to tear streams. Measly teary eyes not included in the list.
Clannad After Story
Demon Slayer Kimetsu no Yaiba The Movie Mugen Train
Violet Evergarden
Violet Evergarden The Movie
Rascal Does Not Dream of a Dreaming Girl
Your Lie in April
I Want to Eat Your Pancreas
A Silent Voice
Anohana The Flower We Saw That Day