I think that's exactly right, and it's well said. "New atheism" was a media creation. I don't know who coined the term, but I'd be surprised if any of the leading "new atheists" did. The movement started when Sam Harris's book sold well soon after 9/11. That tragedy gave atheists an opportunity to make their message go viral on social media, so the media had to cover it.

And indeed, for how long can you keep saying the same thing before the mainstream media get bored of it and move on to the next fad? The movement ended when the mass media stopped paying much attention to it, but obviously atheists and religious fundamentalists didn't go anywhere. Few minds were changed, so atheists joined other movements such as Black Lives Matter or Joe Rogan's or Sam Harris's fanclub. And the White Evangelicals joined the Tea Party movement and then the Trump cult. The latter ascended to prominence as part of the global populist backlash against neoliberalism.

Atheists may be called for again to do battle in the public square, for what it's worth. I find it very annoying that there's no popular atheist publication on Medium, whereas a liberal Christian one like Backyard Church is doing pretty well. It gives a false impression of what's happenning. As you say, Christianity is on the downslide, whereas atheism and secularism are on the rise in the US. (Then again, Backyard Church is only stealing atheism's thunder, by focussing on criticizing Christianity.)