IMHO I think that OpenBSD needs to capable to install and run as a
paravirtualized domU guest, with some limitations if you like.
Last year I have do the same question. Then it was said that only needed NetBSD
do the xen port, and from there just enough to carry to OpenBSD. The reality is
that NetBSD long ago that can be installed and run as domU and OpenBSD not.
And my question is why?? i think that only one developer can't maintain this
type of code ... needs more help. I am not developer but i can do tests if you
needed ....