I love FOF. It’s one of my favorite coasters anywhere. The launch, the disorientation of not knowing which way is up and down, the crazy boost of speed it gets at the end of its course — it’s so much fun. Losing FOF would be a huge blow to the park’s lineup for me.
That said, I recognize that both FOFs are prototypes (don’t forget that they were the very first modern launch coasters ever built) in an era where SF has no patience for these types of early experimental rides. I also have sadly noticed that FOF seems to be having a ton of downtime lately, especially this season.
My only hope is that, if FOF gets removed, SF finds a way to keep the building. The indoor element is definitely the coolest gimmick of the ride. Since KD and KI have identical footprints, that means SF could theoretically develop a new coaster that shares its development costs across both parks. I have no idea if demolishing and then constructing a new coaster inside an existing building is remotely feasible (though the latter has been done, see DarKoaster) but I hope it’s something they’re at least seriously considering.