but even you phrase it in a way that makes it seem like their days are numbered ("it will still be there for a good number of years")
What happens when Lightning gets to a point where it can provide even cheaper instant off-chain trades between BTC and numerous high volume coins like LTC and stablecoins? All with no central authority or limits imposed by the exchanges?
That would be one great moment in history. I can't wait for it.
At that point the centralized exchanges will remain only a gateway for fiat, which I guess that DEXes will be unable to address.