Nissan dropped out.
I like the idea of having a class of lightweight fuel efficient racers though, just too much to sort out with a delta. I also like keeping f1 as a "performance is the only consideration" class as well.
One other issue is the vortex generators creating downforce on the underside. It appears a slight bump into the air will destroy the downforce, as will getting a bit sideways, at which point your tires are skidding (braking) and you don't have the leverage at the front corners to help keep it flat. And people seem to enjoy knocking the delta around
