Tbh, I personally believe DEXs can't really match the volumes we see over centralized exchanges and even if they will, they won't be able to handle it.
They can't at the moment, simply because there isn't the desire in the community to use them. If enough people finally get fed up with centralized exchanges pulling their legalized scams and stealing their customers' coins, then DEXs will easily grow in both size and number to accommodate that.
Even if people get fed up with centralized exchanges and its unwrapped scams, don't you think crypto has already got something new which is working like crazy as it is all based on governance - DeFi? DeFi is already changing things a lot and these swap-machines (like uniswap, sushiswap, etc.), liquidity pools and yield farming has now taken over the game in their hands while most people are able to gain unbelievable rewards for trading there. Shall I call these swap-machines a DEX only? I don't think these come under the DEX category.
I used IDEX (one of the most favorite for everyone going for DEX) but even they had several issues
Given that IDEX requires KYC, it cannot be called a DEX in any real sense.
What? Really? Since when? I used it some time back and it never asked me for KYC then, didn't know IDEX started KYC'ing users.