Much, much rather have Supergirl than Superboy in this franchise.
If anyone should take over if Supes would be gone, it should be Kara.
Top ten favorite theatrical superhero movies:
1. The Dark Knight | 2. Superman: The Movie | 3. Batman Begins | 4. The Avengers | 5. Batman Returns
6. Captain America: The Winter Soldier | 7. X2 | 8. X-Men: Days of Future Past | 9. Spider-Man 2 | 10. The Dark Knight Rises