>Are there symptoms of Clear's demise that signal another attempt to be unwise?

Their primarly failed assumption is that DHS would trust them to clear their customers. There is no possible way that DHS would trust some outsourced security to do their job. This means that every "pre screen" supplier is doomed to fail.

>More generally, how do you feel about the idea of iterating on a model that has previously failed for someone else?

In general, if I think I can prove to myself that I could do a better job (execute it better, if you will), then I would not have a problem with it. I'm more concerned that I'm using intuition instead of real numbers.