Explanations as to why it ended up reduced in the first place and hopefully some confirmation that it will be reverted back to the range she has had the entire span of her existence in this game.
Fearless was actually pretty clear about this.
The range on Q was reduced to make it more risky and more difficult for new Sona to have the same level of poke as old Sona. While poke seems to have been a popular reason to pick her, Fearless' reasoning was basically that you can't have a poke champion and a sustain champion on the same frame because the lane flow becomes toxic.
When a normal poke support gets ahead, you can counter it with poke of your own or a good initiate/cc. This is an inherent weakness of poke support.
When a poke support also has sustain, they are able to widen the gap to the point where counter-initiation is simply not viable. In fact, the opponents will likely start doing less damage as they lose the ability to take risks. There will come a point where the opponents can do nothing but cower under the tower or back. "Once she gets ahead, she stays ahead" is not good design.
If we compare old Sona to Alistar, Nami and (current) Soraka, we see that none of them are nearly as strong in this particular combination.
Nami's pressure comes more from Aqua Prison than anything else and that's fairly binary. It either lands and you're in serious trouble - which is satisfying for Nami - or it misses and does nothing at significant CD/mana cost, which feels good for the opponent. Nami's sustain is also harder to use for full effect because you have to clip an enemy.
Soraka's sustain is stronger, but it's on a much longer CD, which makes for more meaningful decisions. Her poke also puts her at vastly increased risk.
Alistar has potentially the strongest sustain of the healing champions, but he doesn't really have poke. He's a disruption tank like Leona, which means that he has to be in the scrum to do his job.
On a personal note, I think that this perspective on Sona should have been made more clear. I also think that being more direct about the poke nerfs would have allowed him to reduce Q damage but keep the range, which I believe is a more dynamic choice. I would find it more satisfying to be doing things more often, even if the net effect is the same. I think the range decrease made Sona a more passive champion, which is almost always a bad idea in my book.
