We are about to enter a new series of 2D games with Mario in the form of Super Mario Bros. Wonder, so a lot of aspects seen in the New Super Mario Bros. games won't be included. They should however be seen again one of these years, same said about ones from the 3D Mario games that play like 2D Mario games. The ones I'm talking about are:

*Ice Flowers (something unneeded in SMBW due to the presence of the Bubble Flower) *Mini Mushrooms
*Super Bells
*Super Acorns
*Propeller Mushrooms
*Penguin Suits (or some other kind of power up that grants the Penguin Form)
*Super Acorns
*Super Leaves
*Boomerang Flowers
*Gold Flowers
*Mega Mushrooms
*Stuff Like That

It would all depend on the sort of Mario game when it comes to what they get featured in. In addition there should be power up forms introduced in the Super Mario Galaxy games that get featured on Mario's home planet one of these years, in addition to some power ups from games of the 21st century such as the Hammer Flower (which it now would be instead of a suit) and the Super Feather (now with eyes) making a long awaited comeback. Of course each Mario game likes to limit how many power ups get to be featured, and there are those that work better in 2D games then 3D games and vice versa. Mario's next 3D adventure on Nintendo's next system for instance might once again be something where power ups won't be needed, though that would of course depend on the gimmick, and a potential follow up to Super Mario Bros. Wonder might be one to introduce power ups that take a similar take, including another transformation based fruit.