It's difficult to ascertain just how true or false that leak was, but I would personally refrain from treating it as truth unless we hear it from more reliable or official sources.

Genshin is currently in a controversial era. Many players are dissatisfied with varying aspects of the game at the moment, related mostly to Natlan as well as the infrequent release of male characters, and the current atmosphere is perfect for exacerbating tensions. We have to be careful not to believe anything without a proper source.

With that said, however, let's first tackle this question from a broader angle. Some of our other relevant/major characters include:
- Venti
- Dainsleif
- Kaeya
- Albedo

While Dainsleif isn't currently a playable character, he was confirmed to be a future release years ago. All four of these characters are regarded as indispensable to the main story, and all four of these characters are male.

From a writing perspective, it would be an unwise decision to retcon these major characters simply because they're male; it would permanently damage the story and confuse almost the entirety of the player base. Venti himself even has a leitmotif that comes directly from Genshin's opening theme, serving as an additional, larger hint that he will play a major role in the story's future.

While they certainly could change Venti's relevance, it would compromise the quality of the entire story. Replacing him would be an extremely unprofessional decision. This same sentiment applies to all major male characters; Childe's story is no exception.

There's no telling which details of Childe's story have or have not changed over time, but what I can say for certain is that Childe has always been an important character, and his relevance only increases as time passes. They're not phasing him out of the story...quite the opposite, in fact. Instead, they've been gradually building toward his story for the past several years, in some ways people wouldn't even expect.

Even Fontaine, despite its flawed execution of Childe's role in its archon quest, was essentially significant foreshadowing for his future story. This goes for the archon quest, select world quests, and even one of Fontaine's flagship events.

So when you put it all together, think of it this way: with the addition of Snezhnaya, Childe will have appeared in three archon quests in the future. That's more archon quests than any other character will have ever appeared in. And every bit of his lore implies that he's destined for something greater. I could never see a character such as this being removed from the central plot, nor do they seem to be taking that direction.

As I tell any fellow fan of Childe when this topic arises, Childe will remain a part of the core plot, and always has been. Never allow anyone to sway you into believing differently. He is one of the most major characters in the cast. Not simply because he's a harbinger, because his importance extends well beyond that, but because almost every road leads back to him.