To be honest, at this point they can make most champions resourceless or energy based it wouldn't make a difference. They can even remove CDR from the game and lower all spell cd's by 40%, wouldn't change anything.
Mana is supposed to be a way to gate a champion's power, by forcing him to build mana early thus reducing his damages, or build damages but making every spell cast important.
Likewise, if you itemize for CDR you can use more spells but they are less effective.
At least that's how it used to be, now you just build the one or two items that give you literally everything you need : damage penetration AP/AD cdr and an unique passive

I disagree on the second part though. ADCs should actually have more attack speed but less AD, refocusing them on DPS and taking them further away from burst.