I wouldnt rule out that KL is destroyed before Dany even reaches it. Instead of arriving as a liberator or a conqueror she'll be arriving and finding a charred ruin and a lot of desperate starving people.
And there is Euron to consider. If he really wants a massive blood sacrifice KL could be his altar.
But let's say FAegon does gain control of KL, do you think there is any chance Dany will fall in love with him rather than Jon? She arrives and he charismatically offers her a political marriage proposal rather than a fight. It seems like the type of thing book Varys might want.
Let’s look at what we know from TWOW.
Tommen has sent the Tyrells and Randyll Tarly to retake Storm’s End from FAegon and Jon Conninngton. It’s almost certainly going to be Golden Company win, and there’s a good chance that Tarly turns his cloak given that he’s shown misgivings with the child king Tommen and Mace Tyrell took credit for all of his victories during the Rebellion, something that numerous characters have noted.
So FAegon’s got a win there, and that would mean a direct path to KL. Given GRRM’s comments that the Iron Throne will change hands a few more times before the story is done and the prophecy of people cheering the Mummer’s Dragon, it’s likely that he’s on a path to sit the Iron Throne and rule as a false saviour type. He’s one of the lies Dany must slay.
Likewise, Euron’s on the other side of the continent, trying to take Oldtown for the vault of magical knowledge that’s there and the Horn of Winter which is in that area. At the moment his character arc seems to be more focused on bringing down the Wall and unleashing the apocalypse.
Also, you’re forgetting the entire Martell plotline. They want justice and a Targaryen Alliance, but Quentyn’s death at the end of ADWD has effectively burnt their bridge to Dany. FAegon showing up, claiming to be Elia’s beloved son returned from the dead is an attractive prospect for them. Plus Arianne is literally on her way to meet with Aegon as of TWOW, and given what that character’s like, I think it’s more than likely she’ll seduce Aegon and end up as his Queen.
I genuinely don’t believe Cersei will even get her Trial/Wildfire moment. When Aegon and Arianne (the younger and more beautiful queen) roll up with the GL/Tarlys/Dorne she’ll have her meltdown but it’ll be for nothing because Jamie will end her in the same way he ended Aerys.
And if you look at Dany’s arc in the final season of the show, part of her undoing was her identity crisis when faced with the possibility that she wasn’t the true Targaryen heir. That becomes far more of a natural story element when it’s her direct rival who is undermining her role as the Targaryen saviour than it is the love interest who is fundamentally on her side.
what show did, I suspect, is divide Aegon’s role between Cersei (as her direct enemy who drives her to the edge, has the Tarlys/Golden Company in opposition) and Jon (the source of her emotional turmoil that undercuts her association as the last hope for the Targaryens).