What's missing for newer wireless standards on OpenBSD?

My limited understanding is that there is some framework limitation
preventing 802.11n or newer to be implemented. Is that correct? Has
anyone shown interest? Is it a very massive undertaking? Would a similar
change be required again for even newer standards?

This might be helpful :

http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man4/iwm.4?query=iwm&sec=4