[Brainchild]

It did just kind stop. It's a shame too, because it seemed like they'd planned out at least one more OOO form, as the Tatoba model had a streamlined parts-swap system in place, but I'd imagine sales weren't all that great for the Kamen Rider stuff. I know a new ~6-inch line has come out under Figurerise, but so far we've only seen Tiger, Bunny and the Double Chaser in that line. However, it's fairly new, so there's a chance that Kamen Rider will reappear under that. It's doubtful though.
Oh, forgot about Accel World. Some stuff from that also appeared in Figurerise 6.