There aren't a whole lot of milestones in the article that seemed all that memorable...it's a bunch of essentially random things happening, some of which people remember, some of which they don't. It's hard to say what will catch people's memories. Things I might recall:

Five home runs in a game is quite possible - a few hitters have had a plate appearance with 4 homers in the books already, and once you get there, it's a 5-10% chance. Inevitable if baseball keeps going forever, I would think, but it will be cool the first time.

Shutout and hit streaks - I recall Hershiser's run, following it in the papers, but it's not inconceivable it could be bettered. Dimaggio's streak is obviously doable (hey, he did it), but very unlikely.

Cycles don't matter at all to me - especially after seeing a Blue Jay get one by simply not running to second base. Consecutive ones - meh.

I hate pitcher W/L records, but it does not seem there has been a pitcher who has won 20 while losing 2 or fewer (or for that matter, had a W/L% better than 90).  There have been a bunch of 3 loss seasons, including most recently, Cliff Lee's. 

Somebody might do it in my lifetime.  Let's say that it will be Tim Lincecum in the very year he becomes a Yankee...

I agree with the article that Johnny Vander Meer's record is extremely unlikely to be broken - no one else has ever thrown two consecutive no-hitters, never mind three of them. And I can't see any pitcher topping what Christy Mathewson did in the 1905 World Series and throwing four shutouts.

Mick, thank you for posting that article. My hero, older than a child at the time, was also Tom Terrific. Somewhat to the chagrin of my son, who wonders why his middle name comes from a baseball player.

One record that could be broken (and is still relevant) is Ted Williams' record of reaching base in 16 or 17 consecutive at bats. I don't recall the exact number, but I remember seeing that compared to DiMaggio's hit streak once upon a time.

Some stats impress me, others just seem a little flukey. Basically ANYTHING that begins with "from the start of the season" is automatically tainted, especially when you have to combine two different categories (like hits and RBIs) to make it unique.