Well indeed, as of the moment it looks like it is not stable yet the same as how defi started. But we really don't know what will gonna happen if this really becomes the new trend. Though defi will not gonna end but will still continue.
The DEFI and NFT item/coin will never be stable as it depends on the supply and demand. Just take a look at how the price for each item in DEGO finance is going drop as more people earn the item and they will be going to sell it as soon as possible.
The defi trend will remain forever like ICO but maybe there will be some minor changes in the future like when there's a new ICO called IEO that has already done the minor changes from the ICO.
We will see whether people will be hyping the NFT trend or not. The climate in the market is changing very fast.