Pens are stingy on this kind of thing. Only two numbers retired. One guy died in a car wreck and the other is Mario.
Sid and Geno are by no means guaranteed.
Jagr??? That would be an interesting ceremony to be sure. Do people normally get booed at these things? Haha
Sid and/or Geno would have to outright insult the franchise and its fans for their spots to not be guaranteed.
The Pens are stingy with retiring numbers, but as it stands today Sid is 5th in franchise history in games played and will almost certainly end next season 3rd. He's 99 regular season GP behind Jagr and 208 behind Lemieux for the franchise record. Geno is 3 spots lower with 644 GP and could jump Kehoe by next year making him 4th (behind Lemieux, Jagr, & Crosby).
Fleury is also right there, 9 GP ahead of Malkin. That's where the Pens being stingy comes in...Fleury would basically have to win a Cup for the Pens for him in the number retirement discussion.
Win a Cup, not be on a Cup-winner.
Sid & Geno have been guarantees for a while now.
The biggest reason the Pens don't have more retired numbers is because very few players have spent 600+ games with the Penguins. An argument could be made for Coffey, but the biggest argument against it is that he played 331 regular season games for the Pens (compared to 532 for the Oilers). Francis played 1,186 games for the Whalers/Hurricanes franchise compared to 533 for the Pens. Murphy played 336 games as a Penguin (hard to get your number retired anywhere when you play for 5 teams for at least 2 full seasons, but never 6 full seasons anywhere), etc. Barrasso played enough for the Pens to have his number retired, but he's not exactly a well-liked person and all of his records have been shattered by the far more likable Fleury.