I think that support for Mac OS 32 bits if necessary since apple itself, as far as I know, does not have 32 bit version of it operating systems, however I’m a macbook user and I never use any apple workstation.
On the other hand, I think that it isn’t rare to find some machine running a 32 bits version of Windows. I use a 32bits machine in my work running windows.
In my current project using OptiX I chose to use a 32bits version because I have other libs that I have to build a 64bits myself since there is no binary package available (of course, this was a convenience for me but I’m talking about Qt here).
Since this was asked in a public forum, my opinion is that support for Windows shoudn’t be removed as well CUDA 32 bits support. On the other hand, I’m a single user working in a personal project.