Getting back players is also very hard because even with separate leagues is so hard to convince them.
From the already low number of d3 players, a lot of them gave up on PvP after first day of 1.07 ptr, others gave up when 1.07 came live, others when 1.08 came live and they could search easily for public PvP...
With a more and more reduced PvP player base they can't even introduce real pvp ladder and/or arenas... and d3cl has an even more reduced player base and very soon it will become a platform just for the absolute top players... but even they will probably give up because a lot prefer to rofl stomp noobs.
Although I spent a lot on gear and others spent a lot more, one of the only ways for balanced PvP for everybody it will be fixed gear... Or rather fixed stats that anyone can achieve.
A rough example, barbs are allowed to have unbuffed Max 40k dps, 80k hp, 500ar, 6k arm, 7 red vs elites / mel / range 25% block, 15% dodge, 24 ms etc... U can achieve stats in many different ways but with enough testing balanced, and rather cheap to get stats can be found for every class.