Previews need work anyway, since a lot of superfly materials don't preview correctly (or preview at all). OpenGL is getting long in the tooth. But I don't think there is another cross-platform alternative that supports Windows and Mac. Does that mean they would need to start developing for Vulkan on PC and Metal on Mac? Poser isn't a very big development team, that's a lot of resources to devote. I have no idea how the Mac sales compare, but it may be that there just isn't the base of support to justify it.

On the other hand, Blender runs on Metal -- although not for Intel Macs at all, not for AMD GPUs either. So maybe there is room to borrow more functionality and support a subset of Macs? But is supporting a subset of Macs justifiable?

I'd certainly love to see a move to previews more like EEVEE in any case. Dunno if that is possible.

All the GPU spillover stuff... is that relevant? I don't know about you, but I'm not rendering 100 Gb scenes. I'm not even rendering 20 Gb scenes (even though I can). It sounds like bragging about how many angels fit on the head of your pin. Yes, yes, you have a nice pin. I'm sure it fits many angels.