A couple of readers in the Voice of the People section in today’s Daily News, apparently responding to some earlier discussion that I missed, suggested that Johnny Vander Meer’s record of two no-hitters in a row is the baseball record least likely to be broken. 
That could be true, but — and not to diminish the accomplishment, because it’s amazing — it sort of feels like a bit of a novelty record, no? I mean, Vander Meer’s dominance over those two starts is crazy, but it also feels like a crazy run of luck. It’s a pretty safe bet that no one’s ever going to break Fernando Tatis’ record for grand slams in an inning, either.
I feel like the record least likely to be broken that is often overlooked — and this is a pretty record-ish record — is Cy Young’s ridiculous 511 wins. The game has changed drastically since Young played, and so we almost look at that like a footnote more than anything — a novelty itself — but it’s no less amazing. Walter Johnson is the only other pitcher to break 400.
Basically, for anyone to even come close to Young’s record at this point, teams will have to radically change the way they use pitching staffs in some unforeseen way. I strongly doubt anyone is ever again given the opportunity to throw 400 innings in a season — and rightfully so, since so many of the circumstances have changed.
But that dude must have had some kind of arm.
Tedquarters 
I agree with you that the records least likely to be broken will have more to do with how the game itself has changed than the players.
Baseball will always be open to some super-superstar to come along and be extremely dominant–like Pedro Martinez or Barry Bonds were in recent history–but everyone must admit that the game has changed in such a way that certain records probably won’t be broken again.
Dimaggio’s hitting streak, Bonds’ home run record and even Vander Meer’s consecutive no-hitter record are all beatable in today’s game. Given the great number of superb players that we have yet to see and the great number of chances in the remaining history of baseball for extreme coincidences to occur, I think these records are all bound to be broken.
Of course, if baseball, mankind and the universe itself are all everlasting, inexhaustable phenomena, then every conceivable record must necessarily be broken just as monkeys will one day type all of Shakespeare’s works. In fact, somebody named Fernando Tatis will break the record for consecutive no-hitters and somebody named Johnny Vander Meer will break the record for grand slams in a single inning. YOUR MIND IS BLOWN…. Wait, I forgot what we were talking about.
Some trivia: Cy invented the change-up, in order to save his arm some wear. Imagine being the only person in the world (for a time) with a change-up.
A) Vander Meer’s back-to-back no-hitters are more of a feat, an accomplishment, than a record. So I don’t think it’s in the same category as Cy Young’s career wins total.
B) As for Young’s wins record, I agree with you that I can’t see anyone ever being able to come close to that. But the context is important: most of his starts and wins came before 1900, and it’s hard to gauge the level of competition he faced.
That said, a record is a record. Qualify it any way you want, the man has 511 wins, and nobody’s ever going to match that.