So recently a fan asked Rebecca if Peridot and Steven would ever fuse (8:49 in this video) and Rebecca Sugar responded saying:

“Peridot isn’t ready to fuse with anybody, but if she were, Steven would definitely be on the shortlist so it’s a good question, but it’s also okay if she never is. That’s the important thing about Peridot.”

I feel like that alone might not be enough to convince people that she’s never fusing, but there’s also the official fusion for beginners book (written by sugar) that had a page dedicated to each fusion and how they represent all relationships from loving to toxic, and Peridots page was 3 different fusions (Opal, Stevonnie and Garnet) giving Peridot a thumbs up for not wanting to fuse:

So yeah, she might not fuse. I think that would annoy a lot of shippers but it’s a good message. If you just want her to fuse for the sake of having a “wow” moment, her star is appearing soon.