This is how fads work, if you think NFTs are indeed a fad. Look at Beanie Babies and other fads that we've had over time. They spike and then die way down, but some fads never die completely. Personally, I can't say whether NFTs will be around for the long term or not, but I do think they have a reasonable chance for some long term success. We're already seeing things in crypto gaming/metaverse arena where people can use their NFTs to design walls inside their virtual houses.
Here is one article where you can see pop star JJ Lin doing just that inside his Decentraland estate. NFTs are a form of art, and there's a huge market out there for art and has been for centuries now. If a solid method comes around to eliminate fakes/copies and things of that nature, we could certainly see more people in the "live art" world dabble into the "digital art" world.
Nowadays when most people think of NFTs, they think of the monkey you mentioned and the thousands of remakes it's had. I don't know if I see that type of stuff lasting. In the long term, I think NFTs are going to have to be more unique than that. We've seen enough of the monkey now, so people are going to have to start doing more unique things. For example,
here's a 22 year old Indonesian man who made $1M selling NFT selfies These are nothing but simple selfie images, but if you read the article you'll see that each image has a story behind it. For example, one of the selfies is right after he received his COVID vaccine. The best type of art (long term) in the digital world is going to be exactly like it is in the real world - unique!