NFTs are a volatile part of the already volatile cryptocurrency market. Moreover even traditional art and collectibles are hard to value and difficult to invest in if you don't understand the market. Only rule is - we cant predict anything so we can speculate about this.
That sounds general. Here I can give a more obvious speculation. NFT trend will come and goes, just like any trend ever set its foot on the crypto market, from ICO to staking/masternote (even now they show some sign of return), DeFi, IEO,... Whatever NFT can last long or not depend on how fast investors burn out thru it. Give it a few fail NFT then the market will quite down over it.