Sad death but not unexpected.
Here with award-winning turf writer Bill Mooney (1947-2017), both had cancer at the time. Alphabet Soup had multiple cancers if I remember correctly, survived melanoma in 2017. Had been ill for a while and 31 is a grand old age for a horse.
The earliest/oldest Breeder's Cup Classic winner is now either Cat Thief (1996-, won in 1999. Not sure if alive) or Tiznow (1997-, won in 2000 and 2001)
There's a list of horses currently at Old Friends here. Here are the ones with a wikipedia page:
Kentucky:
Silver Charm (1994-), Thornfield (1994-), Sarava (1999-2023), Commentator (2001-), Birdstone (2001-), Awesome Gem (2003-), Nobiz Like Shobiz (2004-), Eldaafer (2005-), Rapid Redux (2006-), Game On Dude (2007-), Little Mike (2007-), Soldat (2008-), The Pizza Man (2009-), Work All Week (2009-) and Stormy Liberal (2012-)
New York:
Zippy Chippy (1991-2022)