Permanent on the 40, and removable on the 70. There was discussion of a limited run of the 40 with the removable wing (Pitts too), but the start up time and cost made a small run too expensive. There didn't seem to be too many folks interested in paying an upcharge, so the plan was set well back on the back burner. It will likely not ever happen, but I can't swear to that as fact.
BTW, a little birdie tells me the Kat 70 is on sale now...
