Could happen. Riot's not likely to implement it remotely near the degree Auriel has it (I play HotS).
Auriel's heal gets stronger based on the damage dealt to enemies by her and target ally. It's basically a support version of Life Steal. The problem is, this forces her to bond with the team's highest DPS character. Burst assassins will let her get off only 1 or two good heals in a fight, Bruisers will net her a few weak heals, and tanks are near useless. So the moment the ADC drops, you lose the support also.
HotS also defines support champions as someone who can heal. Teams regain a lot of health in HotS Fights. This is why Aruiel gets away with such a massive heal. She has potentially (full energy) the second largest per-target per-cast heal in the game (Rehgar's 1st ult/heroic does more for a single target, Lucio's Aura has the potentially Highest HPS in the game), and it applies in a large AoE.
Meanwhile, LoL's modern design philosophy is opposed to primary healers. Soraka gets a grandfathered because it's her only identity since (LoL's) release.