I assume the next iPad will have this as well. Then by next year (year after?) it will be on the Mini and iPhone 6/7C (or whatever its called. Tallest calm down). As for Macs - I'm not as willing to hazard any guesses.
II don't think that's how processor upgrades work. If it were, why hasn't any other manufacturer come out with an all-day phone?You can't simply under clock the processor and double your battery life. Igzo screens, incremental processor upgrades, software optimization etc etc will slowly increase battery life, as phones have done the past few years.Until we get supercapacitors I don't think we will see huge leaps like you hope.
Is there another phone out there that could handle 18 hours of 'medium' use? I doubt it, which makes slagging Apple for it a little weird. My wife's 4 still lasts her all day (i.e. 7am - 5pm, often even later) after 3 years of what I'd call heavy use. Perhaps the 5 is universally worse - but I really doubt it.