I doubt they'll change much, but I'm hoping:
Proper windshield washer.
Electronic parking break or foot break to maximize center console space.
Raised center console, right now they're flush with the seats, I prefer a raised center console which tends to give cars a more premium look (look at Mazda 6 for example, or the Honda HR-V).
Actual armrest and storage, this goes hand in hand with a raised center console.
Move cup holders behind shifter, a la Audi 3, which means a slight tweak to the dashboard and CD player area. Or implement hideaway cup holders into the dashboard like the old BMWs.
I really like having commander controls but I'd be OK with Mazda removing it on the CX-3 so they have more space to work with on the center console. They're not in an ideal place on the current CX-3 and can be a bit awkward to use. That may be more due to the bungled center console. Raising the center console will also help with this if they decide to keep the commander controls.
Power driver seats at the very least as an option on lower trims, and standard on top of the line trim.
Last but not least, ANDROID AUTO AND APPLE CARPLAY! Come on Mazda, your competitors are leaving you in the dust as far as infotainment technology is concerned. I'm fairly certain they won't do this any time soon, or else they would've added it to the new CX-9 that will be released this summer.