Next year ending, if you want good amount of content
For now forget about
-When summer's gonna be back from getting milk (she won't be appearing, she "went" to get milk, then milk got her)
-when thing's gonna end (cause nothing started, nothing began from nowhere, they're all in their meet-up-party stage, they're yet to "began")
With repeated reworks, delays, upgrades and shiftings (yes the dev literally shifts his workspace like every 6 months which further adds to delay, and then starts searching for McDonalds WiFi to upload the recent update which delays things even more) it's better to look for (play/ enjoy) 2 major updates after 3 - 4 years.
If you can't wait atleast that much you'll just suffer, so try to forget about this game rather looking up for updates.
Keeping everything in mind, it's safe to say to wait for a decade if you want the complete finished game(s) {both "summer's return" and "how it ends"}, because I believe the dev is also a good writer and not just a good artist, so he will probably elaborate the story with further 5 more updates, hoping a total of 7 major updates to finish this game. (How can I say all this? I have been following the game updates for last 3 years, hence I know, dev is good but slow, I don't have any official information from dev)
I don't know why you're blind, but better forget about Ocean and Ocean's games for the time being, otherwise get trolled by the bots for enquiring about next updates, as at present there's no update.