He kind of has been, but now it's official. Don't get excited, Kathleen Kennedy haters; she's not fired, and she still writes the checks. https://www.darkhorizons.com/dave-filoni-is-lucasfilms-new-cco/
Ten years ago I would have jumped up and down screaming for joy for this news, but now after Asoka I'm not so excited. Maybe he was stretched to far, I don't know. I guess we'll see. Maybe he'll talk to Lucas for story ideas and maybe that sparks something.
Ugh, Filoni has damaged Star Wars just as much as he's saved it. Ashoka's story should have ended a decade ago, but no way was he going to let his little cash cow die. Anakin's turn to the dark side probably should have peaked with killing her in the Jedi Temple. And don't forget, this is the guy who literally introduced time traveling stargates to the SW universe.
If they can cobble together a rag tag team of Din, Ahsoka, Sabine, Ezra, Boba Fett and Rex (maybe) and have them fight Thrawn then it might work. Rey is not even born yet, I don't think.