I won't be surprised if they come back in one form or another. If I remember correctly, the company that was selling the kits claimed they were being sued because the website wasn't ADA compliant, or some crap like that. Rather than fight it they pulled the site down. This may be completely wrong, or partially correct.
It's such a great design my guess is somebody will either pick up the license to kit them, or you could download the plans from Outerzone and scratch build one.