They still have them but I think they have a different criteria than last minute cash purchase for issuing them. I got one on a HKG-SFO BP a few months ago and I am a Global Entry member. It was the return trip of an itinerary that had been booked at least 6 months prior, paid with a CC and I have been 1K on United for ages. HKG security didn't care but at United's pre-board security, my hands and carryon were swapped and I had a patdown. While I was waiting to be escorted for the "special treatment", the gate agent told me that the SSSS was generated randomly and it could be for elite or non-elite passengers.