One idea could be a story where Mash teams up with an unlikely ally from a rival school. They start off not getting along but through various challenges, they learn to work together and combine their unique skills.
Another option could be a student from a different magic school who is jealous of Mash's popularity and unique abilities. This student could use dark magic to try and bring Mash down.
I can't accurately predict what will happen in the future, so I can't answer whether the third episode of the third season will be released. It is recommended that you go to the official website of the Clear Sky Magic Girl Ilya or the relevant social media accounts to check the latest plot and progress.