No, at the end of the day they just want to work there way, and have their costs covered. They don't want to make money specifically.
I'm sure LFS will get updated in time - you are right that selling a DX8 game when everything is DX12 would be a bit silly, especially as DX8 might not be supported properly by then (backwards compatibility only goes so far).
When EA games produce a sim with comparable physics I'll eat myself entirely
Will LFS last forever? Of course not. You can't expect a one man (programming) band to keep up with physics and graphics all the time. Scawen has chosen, wisely, to concentrate mainly on physics over graphics for the time being (the laws of physics don't change, so get that good and it will remain reasonably good and new stuff can be bolted on in time). Later, when the physics have reached whatever standard Scawen decides is 'okay' we'll get graphical stuff, maybe meaning a new version of DX.
A community 'rumour' is that this point will be S3, so the majority of the physics stuff will be done by the end of S2 (no including stuff that requires the graphics first - rain for example). How true this is will only become clear in a few years time. I look forward to finding out.