Out of curiosity, just checked their website. No mention of them going out of business, although it would not let me try to book anything beyond Dec 31.
(Last month I had a SS ride booked to Love Field. They sent me an email 2 weeks prior to the reservation date telling me they were closing in DFW and refunding my $. I checked the website then, also out of curiosity, and noted the same thing. No mention of their ending operations. Ended up booking a car service.)