Just the performance optimization,stability and some extra optimizations for iphone 4/4s (LOL i have 4s)
I know Apple won't do it in 7.1 but What I think is
By Making the iTunes app approval process bit more tight and from their own side,Giving the apps bit more room to integrate seamlessly in their OS..So a good tight
developing design + integration will surely be the most most most productive and practical change ever...
Like Clock app integration to alarm apps,Download manager,a "really well designed" file manager integration,keyboard apps integration into iOS,or having some sort of app persmissions to use the keyboard for apps
Allowing backgrounding of clock apps and etc,Ability of stock apps Like notes and reminders (maybe even calender) to access lockscreen,NC to have them all the time in NC/LS....would be extremely productive
EDIT:
Was just thinking that possibilities are endless,like integrating Launch Center Pro into CC/Lockscreen (swipe left and here we go essential apps on lockscreen,click on the app and hit the thumb on Touch ID
)..."launch center pro requires the permission to access lockscreen"
Ability to have Reminders into NC/Lockscreen all the time,Notes app integration into stock app
etccc
"iOS at present is like a beautiful piece of writing ,yet to be converted into an aesthetically crafted prose"