So it means if politicians one day find out that criminals use centralized exchanges as well, cashing out via centralized exchange won't be any better than P2P or decentralized, right?
I don't think it will matter. They know banks are used by criminals, but banks consider money from other banks clean.
It seems to me like you need some sort of 'government-approved party' in your crypto-to-fiat-path to prevent issues with larger amounts. What if new exchanges are going to be based in a crypto-friendly country like Portugal or El Salvador; such an exchange could probably get away with accepting all UTXOs, without blacklisting, while at the same time being 'governmentally-approved' so that banks won't need to thoroughly question source of funds when cashing out.
Something tells me receiving a bank transfer from El Salvador (which
has one of the highest crime rates in Latin America) will be a big red flag.
Portugal won't help much, it's part of EU and thus has to follow EU legislation.