actually dipshit at the end of the movie rei specifically says that "Anyone can return to human form as long as they can imagine themselves
in their own heart."which means that anyone who disappeard during third impact return.so
that means that shinji and asuka are not the new adam and eve and that everyone can come back if they choose to...yui's final line "Don't worry.
All living things have the ability to return to their original form... and the heart to go on living.
Anywhere can be heaven as long as you have the will to live.
After all, you're alive... and you can find the chance to achieve happiness anywhere."