Why would that make any difference? Most of Bitcoin is already held in centralized databases by companies. Bitcoin stopped being "decentralized" in terms of the way most people use it on a daily basis many years ago.

As for what can stop the current bull run:

1. A US recession or the threat of one would cause all of the crypto bros to sell their BTC so they can pay their bill = BTC crash.

2. Another FTX-like event sets off a "fool me twice" effect in people's minds = BTC crash.

3. A few of the current Bitcoin whales who hold 80% of Bitcoin want to diversify, or get a little nervous, or just have some brainfart against their Bitcoin holdings = BTC crash.

4. People read this thread that demonstrates that there's lots and lots of things that can make BTC crash so they dump their holdings = BTC crash  .