For online play a forge 1.8.9 version would be a very nice, as this is where I personally play the most but I am not sure if its quite possible since 1.8.9 is an entirely different version. Still would be a cool thing to look into

if forge is not an option just a non-forge version for 1.8.9 would be nice

1.8.9 is a vastly different version, containing an entirely diff rendering system & world system + this

It's not being considered. Please try to search before opening issues.