It's quick and it's dirty, but it gets the job done; yes, it's the TSA Blog's Response to your Clear questions. Although most of the post is devoted to reminding people that this whole debacle is not TSA's problem, but Clear's and that's who should deal with it, they nonetheless remind us that two other such companies still function out there: Flo and Vigilant.
Beyond that, the TSA assures that the market for such expedited security cards is still open: "This is purely a market-driven, private sector venture offered in partnership with airports and airlines. Another vender could potentially take up the program." ]]>