Is Starfinder doing okay? Or is it already beginning to plateau, or even die off?
Don't know about anyone else, but I'm personally losing interest and jumping ship from starfinder. It's combination of several factors, but it's mostly a disconnect of what the game offers and disapproval of it's rules. Our group is used to narrative/roleplay first type of games like Call of Cthulhu and World of Darkness. One of the reasons our group has put up with starfinder this long is that we have a great GM that chooses logic and roleplay over arbitrary paizo-isms.
I think the real problem this game has is that it feels like a video game. It has a bunch of ideas and conventions that make sense when applied to that space, but here on the table where's there no computer to do all the behind the scenes work, it feels clunky because you gotta flip to three different pages to get all of those little rules cogs to mesh together.
As far as Starfinder goes I still feel the community impressions (and thus your player's impressions) are out of sync with the mechanics. The art and layout all have a sci fi look, but in reality the mechanics and game play are tuned for something like Borderlands and Destiny: shootem up and take their guns. That's a fine idea for a game and even interesting. But I found so many folks were trying to force sci fi on it, and had rightfully expected something like sci-fi, because that's what the game presents as in its visuals.I blame a lack of good sync between James Sutter, the creative lead, and Owen KC Stevens, the design lead, for at least some of this. During the publicity cycle Sutter was out front and talking Firefly and Shadowrun and even Star Trek as touchstones. Not a word about borderlands or Mad Max style stuff.
I think as time goes on, more and more people likely realize starfinder isn't a real science fiction game, but fantasy with the veneer of sci-fi like warhammer 40K. And that it's not a really roleplaying game, but Borderlands with RPG elements.
Our group wanted a Fallout 2 experience, and we got Fallout 4 instead so to speak because of that aforementioned disconnect between the game's presented aesthetic and mechanics.