Will this mod be updated for 2.0? It was very nice and pretty to enjoy, and it'd be cool to be able to continue using it.

Given the activity, I guess we won't get an update. I hope I'm wrong, though.

Until then, Noxys Trees might be an alternative.

I wonder how the author would feel about a spinoff or something like that? Just enabled it to learn it's no longer compatible.

As it is licensed under the unlicense, I would suppose they wouldn't mind, if they abandoned the project.
At least personally, I would feel honored if I made a mod that someone would value enough to pick it up and continue maintaining it 4 years after my last update. (If someone does so, please leave a note in the discussions, preferably in a new thread, to make others aware, and as usual, mention and attribute the original author in the fork.)