You can't chock up mediocre theme park attendance to "Oh my gosh, the franchise is dying!". Theme parks, unlike movies, are things that you don't necessarily want to go to as soon as possible the moment they're open. LucasFilm and Disney announced three attractions/rides for Galaxy's Edge, only one of which is currently open at only one location. Only one attraction means there's less to do, which means longer lines, which means less fun. Once the other attractions get up and running in the coming months at more locations, I'm sure traction to the park(s) will pick up.
Also, theme parks are expensive, and Disney raised their prices right when Galaxy's Edge opened, which means there's even less incentive to go. If anything, this signals that theme parks may be falling out of favor rather than Star Wars. On top of this, you can't say kids aren't interested in the franchise anymore because they're not going to the park. They don't dictate when they go to the park, their parents do. If they're parents want to save their money and go when there's more to do, then I think they're being smart. Get as much bang for your buck as possible.
And on the topic of toy sales, that's more a discussion about how traditional toys aren't as big with the 7-10 crowd as they used to be and not so much the franchise they're associated with (and even then, I haven't been too impressed with Hasbro's offerings the last few years outside of The Black Series, but then again I've never really been into the traditional action figure much).
Honestly, you can hardly call this an "article". It's essentially clickbait that says "So this is a thing because reasons" and doesn't do a proper job of backing up its claims. Most articles on Star Wars nowadays are like this, because people know they'll generate clicks, and it obviously works, which is another reason why I'd argue that it is not dying out anytime soon.