(March 11, 2022, 7:23 pm)MabDos123 here's another link with additional information:

https://www.tokyoreporter.com/entertainm...ragic-end/

in the article it is confirmed she was indeed pregnant and near due date.
her cause of death is also narrowed down to brain hemorrhage/thrombosis.

I am actually curious now if the AV they were shooting on that unfortunate day was ever released. and if so, where a copy could be procured.

Everyone on set that day was likely traumatized by what happened and probably agreed not to release the unfinished film.

I don't know if it's released or not.
maybe @monyek can help answer it looks like he's originally Japanese

According to the Japanese wiki, three films were released after her death. The tribute one and two that she recorded shortly before the incident.

It's uncertain when exactly the films were recorded or if they include her final sex scenes. It wouldn't surprise me if they went on ahead and released it and edited out the scene where she collapses.

They released a memorial film, so it wouldn't be too shocking if that also happened.

1. Is she really passed away?

Yes. Like many others pointed out, she has passed away and  the news is even on 産経新聞 (a legit news).

2. Has her last JAV released?

I think so. Based  on the available news, the last AV she was shooting is "美人妊婦容子":
   

This JAV was released on 2009, after she passed away. 

I doubt the AV studio will release any additional footage (especially the footage of she passing out), because: (1) they might have stopped the shooting as soon as she felt unwell (she felt unwell after the JAV shooting was finished, and passed out during an interview session. I have not watched this JAV, so they might have included the interview session in the beginning of the JAV but excluded the particular scene), (2) police was involved in the investigation of this incident (the AV studio may want to avoid getting any troubles).

3. Her pregnant JAVs
   

She has pregnant twice, and has shot pregnant JAVs for both pregnancy. During her 1st pregnancy, she used the name of "白井エリコ" (shirai eriko). After giving birth, she also did lactating JAV, with the same name.

During her 2nd pregnancy, she shot JAV under the name “石野 容子” (Ishino Yoko). She passed away during the 1st shooting. 


Wish her rest in peace.