Of course, there is no 100% guarantee that this will not happen, but I am sure that if major countries block exchanges and cryptocurrency, following the example of China, these exchanges will simply open under new jurisdictions and continue to operate. It is impossible that absolutely the whole world is against cryptocurrencies. Cryptocurrencies are a business and it is bound to benefit someone in this world. The crypto industry is mobile. Remember how miners simply changed their location after the ban, the same will happen to exchanges. Yes, the market will be shaken by such bans, but after exchanges reopen in other places, the market will start to recover, just like the hash rate recovered after the Chinese ban. It is impossible to ban cryptocurrency completely.
If governments unanimously rely on a "One World Currency", then it's probable they will ban crypto altogether. But it's very unlikely we'll ever see such a unified currency, since countries can't reach a common agreement. As long as this is the case, it will be impossible to ban crypto for good. Even if they did, crypto will still survive thanks to its decentralized and censorship-resistant design. Centralized exchanges only constitute a small portion of the crypto ecosystem, as the rest is dominated by miners, stakers, and even decentralized exchanges themselves.
What matters here is decentralization. With it, crypto will be able to stand the test of time regardless of a government crackdown or ban. Who knows if crypto lives alongside Fiat for generations? Just my opinion