Peach won't pop. Why? Because her entire kingdom depends of all the coins she's struggling to keep inside her, as the Mushroom Kingdom has been in a constant state of bankruptcy due the constant attack of it's neighbor the Koopa Kingdom. Besides, keeping all the kingdom's money inside her will make her way too heavy to get kidnapped by Bowser ever again. She just has to keep on, slowly getting more coins so her stomach will get used to the pressure and won't rupture.



Aaalso it seems the excessive pressure it's making her feel something else besides pain or disconform. Maybe that's the reason why she has gone so far till now.