If Blackrock makes their own fork, the shitcoin would likely be a security and they’d be subject to all sorts of liability that wouldn’t have existed before that. That would also be a $1T gamble that no sane company would make, especially if they already recognize bitcoins value - which they do, because they’re making an etf. The incentives just do not align. Why launch an etf, which is specifically made to derive value from an asset, and then try to undermine that asset via placing a massive bet that everyone will just follow you over to you’re centralized security token.