No, it can never get close enough due to the problem of burst, they'll always have a reason to increase mana pool. Suppose for a second Ret wasn't CD limited but resource limited, and this was achieved by giving them a small mana pool and mana returns from JotW would cover the desired DPS. Then for PvP rets would stack extra Int and do crazy initial damage, ret-holy would be the new prot-holy.
Let me put it another way, imagine for a second that there was +energy gear out there. No matter how horribly itemized it was for sustained DPS, rogues would be loading up on it for PvP. Essentially all the caster mail/plate would act like +energy gear if mana-melee wasn't CD limited. There's no remotely elegant way to avoid it.
So lets not start hoping for another mana/melee class, because we might get one, and it would suck. It would have to be CD based and would end up a bad copy of enhance or ret - two specs that are already arguably too similar in feel.