Once ETH tries to get everyone into PoS, that's where I think problems start.
If ETH weren't so established right now through the NFT marketplace, I might suspect you'd see a jump to other blockchains, like Bitcoin, that are still on PoW. Since it is established, I worry that people will try to make it work for a few years, but it ultimately won't work, and ETH Mainnet will either be forced to revert to PoW or lose popularity to another fork.
While NFTs are a non-negligible component of trade volume on the Ethereum blockchain, numbers I've seen recently put monthly volumes of e.g. OpenSea in the single-digit USD billions equivalent. The daily volume of ETH is currently about USD $14 billion equivalent. I don't think the NFT marketplace is what's greasing the wheels.
When you have way more forces in the market, many who aren't motivated by making it work, I think that's where PoS has some real weaknesses, and I don't think we'll see practical attacks against it until one of the important ones goes PoS.