This week I finished watching Kill la Kill. It was a lot of fun. Absolutely wild ride. Still, I can't help but think that Tengen Toppen Gurren Lagann executes a similar concept better. I loved Kiryuuin Satsuki though. What a great character.
For this summer I think Dandadan Season 2 and City are the most obvious contenders. I'll also definitely be taking a look at Hikaru ga Shinda Natsu (rough translation: The Summer where Hikaru Died). It's not that I'm particularly interested in the concept, but the manga is well-reviewed and Cygames has been absolutely killing it lately so I have a certain level of confidence in their ability to execute now.
I hadn't really considered it, but you're right. There's no reason Naddy's mom would be off the table other than maybe having too much overlap with Yaku. I'm still guessing it'll be her sister though, and that the aforementioned sister was also the ninja we saw at the end.