In my eyes, this would be about, when is this game "really" abandoned or not. As I do not know this and sadly I have the same insight on the current state of the dev as all the others.
If I would have some thoughts about to carrie over the game from the dev, I would like to have his consent. In regard of this, I believe this is quite impossible as I don't know any other way to communicate with him/her than over patreon and even then I would assume that he/she would recent your proposal - only my humble opinion.
Also I think, you would have a hell of the job with this project. They would be a lot of hat that you "stole his/her game" - even if he/her gave you their support - and also a big portion of "you ruined it", "he/she could made it 10 times better" and so on.
I would say regardless of your talent and even if it end well, the first few updates from you would most likely cause a shitstrom each times.
About the many active patreon support for the dev: Only way to know immidiatly the last news about the game
And me too every time, I look at this thread I hope I read some life signs about the dev or the game