The Ending for Gurren Lagann was sad
That's why I don't think it should be the ending.
Picture this. A thousand year later, Simon (he is alive because he is made immortal by the spiral energy, just like that black guy) finally discovery a way to revive Nia by invading Heaven and defeating God to free her soul. To do so, he'll need the help of his former comrade. He'll wonder around the universe to find their remains and using the DNA left behind, he'll use spiral energy to regenerate them. With his team back and alive, he'll recreate Gurren Lagann and use it's drill to pierce a hole through the wall of Heaven. Then they'll fly through Heaven in that badass battleship, Cathedral Terra or something, fighting angels, saints, hired demons, the Devil, Jesus, Moses, Abraham, Mohammad look-alike, and then finally God. During the confrontation with God, Simon discover that God is a giver-upper because God had initially intended for everyone to live in paradise unaffected by time/evil-ness but soon gives up that dream due the realization that human are inherently evil when Eve/Adam ate the apple without his permission. Afterward, God banish the human and reserve Heaven for only the good human. Simon defeats God and just before dying, God gave the responsibility of the both the spiritual and physical universe (not like that Anti spiral guy that only gives the physical) to Simon. Simon accepts the responsibility in a cool heroic fashion, bring Nia back to live in the physical world, then have Rossius handles the universe for him as he and Nia shack it for all of eternity.
During the invasion of Heaven, Yoko absorb some heavenly powers which caused her breast to grow even bigger and cause her to grow pair of angel wings on her back. She then wears a white bra and a white hot mini skirt.
If you want an ending like that read Spawn. He almost single-handedly defeated the armies of heaven and hell, and then recreated the world.
Yeah, that isea sucks. If they are going to make a sequel then it would be about this other threat they mention in the end about spiral energy destroying the universe or something like that.