Notice, NSMB4 is currently delayed for an indefinite amount of time. Powerups are back! Rather than finding them by hitting ? blocks, you spend 15 Starbits to activate them (I may nerf it to 5 or 10) kind of like in DK Bananza. You won't get all the powerups at the start of the game, but how do you unlock more? You'll see when the game releases.
I'm planning on having more powerups for NSMB4, but I have no intentions of adding the special powerups from NSMB3 (Super Star, Flying Blue Shell, and Destroyer). Fun fact: I am recoding the powerups to have 0 clones, but they should still work the same as in NSMB3.