Underwater Ruins (Adaro, Gopherga, etc.) will be gone after maintenance 9/10/2020 ?

Or they remain till the end of „Saltau's Beach“ Opening Period (9/17/2020) ?

I tried to find the answer on the official site, but can’t find any news containing this information...
If I overlooked it, please post a link.

 

They might remain at 17 but no more diving I guess and summershell drops.

 

Yes, Mini Game "Diving" Period and Summer Shell Drop Period are crystal clear...

http://en.toram.jp/information/detail/?information_id=5528
Mini Game "Diving" Period
From: 7/30/2020 after the maintenance
Until: 9/10/2020 before the maintenance

https://en.toram.jp/information/detail/?information_id=5529
Summer Shell Drop Period
From: 07/30/2020 after the maintenance
Until: 09/10/2020 before the maintenance

 

as long as the beach is open, so should the portal to the ruins.
but the quest might be disabled along with the diving game.
so you can just exchange your remaining points for rewards.

 

They said summer event limited quest period until 09/10/2020
http://en.toram.jp/information/detail/?information_id=5565