Yeah, that's fair. Staying in the past doesn't work forever. There are scars in the implementation which suggest the HSA model was really difficult to implemen

Yeah, that's fair. Staying in the past doesn't work forever. There are scars in the implementation which suggest the HSA model was really difficult to implement on the hardware at the time. It doesn't look like old hardware gets explicitly disabled, the code that runs them is still there. However writing new things that only work on newer hardware seems likely, as does prioritising testing on the current gen. So in practice the older stuff is likely to rot unless someone takes an interest in fixing it.