It's like talking to a brick wall here.
I am more concerned about the hardware than I am the software aspect.
Progression of the physics will eventually need a hardware boost. Start adding things like weather and engine breakdowns or other mechanical errors that will need some sort of calculation to determine these things and you are eventually going to hit a ceiling when catering to this older hardware or hardware that doesn't have appropriate support because it is on an OS that isn't supported like Windows is. I know you want to cater to Mac and Linux, but from a business standpoint. Windows has and will remain the dominate platform for PC gaming. There are plenty of ways for Mac and Linux users to use LFS without having to specifically cater to that specific OS. This seems like a dragging the feet kind of method if you ask me. On one hand you want to progress LFS and make it better and add more content/features but on the other hand you are worrying about a fraction of the player base because you fear they won't figure out a way to play LFS because of OS issues. LFS fans that use all 3 platforms will certainly figure out a way to play LFS if there is much more development progress going on. At this current pace, I see everyone leaving and complaining because again, the developers vision doesn't match what the player base wants.
I think it is pretty clear that over the last 5 years since the announcement of VWS and Rockingham, people are more concerned with having the game updated and refreshed rather than all of this other development that has taken place.
If the developers want to keep being blinded by their own view for LFS, then go ahead and continue down this path.
Whatever you decide to do, you will always have someone that is upset. The question is, do you want to have a majority of the player base upset because of the lack of progress or would you rather have a fraction of the player base upset because of loss of support of hardware/software.
In any technical situation, there will always be a point where in order to progress, you have to force those that use your product to upgrade and purchase something that will perform with you technical advances