Remember that it's about +4-6 months past graduation for a Hololive gen. Mid summer actually makes sense.
I wonder where this myth that hololive take 4-6 months past graduation comes from so I actually went and check.
Almost all hololiveEN members never graduated their pl and only purge vods and went on hiatus. There are only 3 independents graduated out of 15. For those 3, only Mumei & Bijou made a graduation stream, whereas Nerissa silently killed off Mom0ki and rename all her channels into Caitlyn Myers. Hololive does not request graduation and most people keep them as an option for life after hololive.
If you remove all the variations (corpo graduations, myth due to flesh/first gen, Irys still regularly streams as Namirin, Bae announcing graduation on the day of debut)
the average between last stream til debut for hololive members are 2 months
So 2 months from now would be April, I highly doubt that they going to release EN gen 4 on April + the fact that hololive doesnt request graduation, they are not going to hololive.
If there is an org retarded enough to require graduation, nijisanji is the only one that comes to my mind.
Fun fact: keekihime streamed on twitch 4 days AFTER she debuted as kiara, because why the fuck not.
Full chart: