Not particularly Stop 'N' Swop, but I definitely want tons of ridiculously secret easter eggs hidden in the game, some of which may allude to mysterious things that are only fully revealed/understood in other Playtonic games. I.e. foreshadowing.
I really loved Banjo Kazooie for the mystery surrounding Stop n' swop. Not to forget the devil bottles picture from Tooie.
I recently had a discussion over at Reddit about how a dev could still hide secrets in its' game without getting them data mined right away. I guess the conclusion was it's not worth the effort because it would take some sort of encryption or major obfuscation or garbage data in the code.
Still... I remember the promise of secrets that could take months to discover... wonder if Playtonic really has a ace up its sleeve or if they were false promises after all. Can't wait to see! I'll make sure to avoid the internet after release for a while!
Updates and DLC could actually come in handy here. The game can have something visual like that Ice Key without a clear function and also don't have code that gives the surprise away because it will be added later. Of course I'm not a programmer so I wouldn't know if that's possible.