For me the game would be as it follows:
Start a toon. You would start by doing initial quests and gaining some shit gear. then move up in levels by doing LFD. when you felt like you were good enough, you would enlist yourself in pvp battles which would be the first way for you to prove yourself in game and win rewards that later on would get you invited into raid groups depending of your track record. In raid groups (there is no longer LFR) you would be able to win legendaries and only one level of tier gear.
To be honest I actually would prefer this idea if there were no lvls in toons and in gear and shit so any epic weapon would be as good as any other epic weapon and so on. But this woul make Blizz eat their own hair trying to come up with challenging dungeons and raids where player's lvls didn't matter, but plain old skill.