there's no more plot to explore and the main characters have accomplished all their goals, I think it's just another 1 season hit like TTGL and similars
~~You haven't heard what Ragyo said after the final battle.
I won't go into further details because I don't want to spoil people who haven't watched the episode. But let's just say what Ragyo said is quite similar to what Lord Genome said after Simon defeated him.
Season 2 is possible.~~
Scratch that. I just remembered Gurren Lagann never have a follow-up even though Anti-Spiral warned them about the upcoming Spiral Nemesis.