The Belmont might not, esp. since that distance is hardly run anyway and they won’t generally train for it.
The others definitely possible. Monarchos’ Derby was sub-2:00, and actually 3 other horses ran the Derby within a second of Sec, including the solid Decidedly in 1962, and the great Northern Dancer 2 years later who was known for hitting the 2:00 mark.
Sec’s mark on Preakness was adjusted,so it could be questionable, but, as it is many horses have been within a second of that, including this filly in 2020 (the year I didnt watch AT ALL since the jockeys and track owners were kneeling for these riots so I don’t recall any of this) very close.
Monarchos ran 24 years ago. In the past 15 years ONLY ONE horse (Authentic) has even run below 2:01.
I read a long article a few years ago that talked about changes being made to the track surface to help prevent injuries. They seemed effective, until last year, but... they make the track softer, and thus slower.
So, it could well be a very long time before Secretariat’s record at Churchill is broken. Unless of course, they change the track again to speed it up.