I honestly think we’ve seen the magic of TLK from Emma with Henry, therefore it would be kind of odd to say that her “romantic true love” is somehow more important and able to achieve something that what she feels for her son could not. It might come off like romantic TLK is more powerful than maternal TLK.
I’m expecting something with Regina and Henry frankly, though I’m far from an Evil Regal, it just would fit more thematically for this season, whatever may or may not happen in Emma’s love life. I believe Regina’s motherly love for Henry is going to be a huge factor and we have yet to see that proven as every bit as true as the love Emma has for Henry. I feel the writers are driving towards this conclusion.
“If I had a world of my own, everything would be nonsense. Nothing would be what it is, because everything would be what it isn't. And contrary wise, what is, it wouldn't be. And what it wouldn't be, it would. You see?” -- Lewis Carroll, Alice's Adventures in Wonderland & Through the Looking-Glass