All of these records are safe. Their chances of being broken are extremely remote, if not impossible. Eleven and one-half, nine and one-half, and almost eight decades have passed, respectively, since Reulbach, Wambsganss, and Vandermeer accomplished their feats. And 150 years passed before Tatis exploded into the record books in 1999.
(I remove the killing of Chapman; the possibility of a ballplayer getting killed twice on the field of play strikes me as too metaphysical.)
So let’s run down the likelihood of each record being bested, in order of most likely:
(4) Ed Reulbach’s double-header shutout. This is not beyond plausibility. The main obstacle is today’s specialization of relief pitching and its effect on starting pitching. It’s unlikely in this era that a pitcher starts both games of a double header. Hell, double headers are rare! The point is, however, that this record is more vulnerable than the other three—if a trend toward complete games should ever return. A pitcher would have an entire career to pitch two double-header shutouts.
(3) Bill Wambsganss’ unassisted triple-play in the World Series. A player might have to get in multiple World Series. He would have to pull off two such triple plays. There have been only 14 unassisted triple plays in regular season play, about one every 10 years. So Wamby’s record looks safe.
(2) Johnny Vandermeer’s two straight no-hitters. I see this as less likely to be broken than Wambsganss’ feat because it would require three straight no-hitters, compared to two World Series triple plays over an entire career.
(1) Fernando Tatis’ two grand slams in one inning. Consider that two grand slams by one batter in ONE GAME have occurred only 12 times. To break this record a batter would have to come to the plate with the bases loaded three times in the SAME INNING. He would have to be at least the 4th batter in the inning with the bases loaded, then the 13th batter with the bases loaded, and finally the 22nd batter, bases loaded. In the entire history of major league baseball, the same batter has come up three times in the same inning only 28 times (17 since 1900, the modern era)! To come to the plate three times with the bases loaded? One source puts the odds at several hundred billion to one. And this says nothing of hitting a homer each time up.
If our planet survives as long as the time since the Big Bang (almost 14 billion years), and if baseball still exists, Fernando Tatis can spend his dirt-nap without once rolling over.