As it appears there is no interest in oneboxing Wikiwand, I've developed a solution for those of us who use it. Install AutoHotkey, and run this script:
#IfWinActive Google Chrome
Ctrl & c::
ClipSaved = %clipboard%
StringLeft, URL, ClipSaved, 23
If URL = http://www.wikiwand.com
StringTrimLeft, article, ClipSaved, 26
clipboard = http://en.wikipedia.org/wiki%article%
While this is running, any time you copy a Wikiwand link, it will convert it to a Wikipedia link. It won't affect you, as the Wikiwand plugin will automatically convert it back to a Wikiwand link when you attempt to visit it. It will, however, make it so "Wikiwand" links will onebox when you copy them into chat.
This version is for Google Chrome, to use it for other browsers you will have to replace "Google Chrome" in the script with the name of your browser as it appears in the title bar.