Does Haiku plan to support restricted memory mode W^X, in order to reduce the chances of infection?
That doesn’t reduce the chances of infection, that just reduces attacking vectors.
Reducing attack vectors… is a significant factor in reducing chance of infection.
I believe that Haiku already does enforce W^X in kernel memory as mentioned in the December progress report and in hrev52632 and on wards.
Not even Linux fully enforces W^X for userland applications by default yet, only OpenBSD does, as far as I know. So it will probably be some time.