**Potential Speculative Spoilers**
Here's hoping for:
Alto survives the explosion via jettisoning from his fighter
SMS scoops him up and allows him to return to his VF-25
Sheryl gets word that Alto survives and is returning to the fight
This cheers Sheryl up and allows her to...
Continue the singing battle against Ranka
Brera snaps out of his trance and is able to briefly "wake up" Ranka.
Reveals that they are siblings and share a brief moment before...
Alto taking Brera's VF-27 out of commission (Not destroying)
Message gets to SMS that Grace is manipulating Ranka to her own gain.
SMS turns to Attack Grace (some how) allows the hold on Ranka to release
The Vajra are now used against Grace thanks to Ranka.
Meanwhile, Sheryl is going through a coughing spat and cannot sing. She Discovers blood in her mouth and passes out...
Big final fight occurs here SMS/Vajra vs Battle Frontier
SMS wins... Vajra are some how forced to stop fighting
Battle Frontier is boarded and Leon is arrested, he ends up committing suicide by disarming Kathy and putting a bullet through his head with her gun.
Luca discovers that the V-type infection actually has a 75% chance of not being terminal after all. Its discovered, after reexamining her, that Sheryl is actually suffering from Mild Hemoptysis and the common cold. The medication that Grace was giving her was making the cold persist. She is cured immediately(Nano machines?).
Alto finally chooses, who he wants to be with... Its Klan. (I'm serious)
In all reality... He chooses to return to his Father's side and do one final Kabuki show before his dad passes away. Because of this Sheryl stays by his side and she finally reveals her feelings. Alto finally accepts this.

Ranka, chooses to remain with the Vajra and not stay with the survivors of Frontier on their new home. It is noted that the Vajra are really peaceful creatures forced into battle with the loss of their original queen. Ranka takes place of her mother and chooses to live with them and her Brother. They leave the planet to find a new home.
It is announced that the story of Alto and Sheryl will be continued on their new home world... With a new threat of course. Due the the popularity of the show, They will either do a second season of 25 more episodes or a 5 episode OVA and a movie(A la Macross Plus).
Now this is all my ideal wrap up of course...