I vaguely remember that discussion. I also remember a suggestion of "super-charging" her Power Chord. After 3 charges, it could be further charged (to a cap as was agreed infinite-charging shouldn't exist.) Something along the lines of "after X additional charges, it combines multiple Power Chord effects or gains an increased effect."
On the other hand, if you're suggesting she become Invoker, that idea has been decidedly shot down by both players and Rito on every occasion it came up.
Power Chord weaving is an interesting concept, but right now the correct fix to the "Staccato-spamming" playstyle is to fix Sona's cooldowns. The reason players spam Staccato, the **main **reason, is that Hymn of Valor simply has the highest uptime. Staccato has the easiest accessibility for players. Fearless knew this would happen if he gutted Sona's cooldowns, but he did so anyways. It happened, players pointed out why it happened, he ignored us and nerfed Sona rather than fixing her. Players became angry. Nerfing Sona's cooldown, not allowing her 3 spells to have the same cooldown, directly negatively affected Sona's skill expression.
Sona's original kit had more decision making than "cast every spell every time they're off cooldown" like her current kit is. Sona literally doesn't do anything without casting spells, all of her Power is trapped in activating spells, so her playstyle is cast everything always. This mindless spell-spamming became more mindless when her R passive was changed from trapped power into trapped power a'la URF-style in patch 6.14.
People **CLAIM **Sona was a "walking stat buff," but Sona was never **PLAYED **as a "walking stat buff" except literally in Bronze games. Which explains why Fearless fabricated that fallacy, since he was Bronze 1/Bronze 2 when he was busy reworking her. No Sona player Silver+ would be caught dead being a walking aura bot. This isn't how you utilized Power Chord, this isn't how you utilized the +20 AD and AP you gave yourself with Hymn. This was merely an excuse for Fearless to create a failed design, which isn't even my biggest problem with the kit, nor the real reason it failed.
Patch 4.13 was a failed design, solely thanks to her trapped power in R-rank passive. She was gutted because power was trapped in R ranks. She's still unbalanceable because of trapped power in R ranks. Trapping power in R ranks inherently contradicts basic support-champion design. Once Rito dumps her passive on R, she can finally become a healthy character again, but not before that.