I do not see this BlackRock's entry as a breakthrough for cryptography, rather an attack on future network decentralization.
Im not sure though. Bitcoin's utility is a store of value now the world works with money involved with it. This people who are interacted with bitcoin for investment scheme can also have their freedom to do so. Well they are using bitcoin though as Satoshi wanted too. Anyone can use bitcoin for peer to peer transaction, if you are aiming for that then these huge people are included also on those Satoshi's goal whether they use bitcoin big or small. They may have agenda for themselves but that isnt out of control.
I understand, but my biggest fear would not be these big companies themselves using Bitcoin for capital gains, and thus having the power to influence other users and miners to follow their fork. I could be completely wrong and doubting the miners, but it would be very naive to believe that the miners would stay in the main network just to reap a little reward, there would be no incentive from the network to protect it, and the block reward would not pay the expense of machine and energy. I think in this way that in the future the fork could harm the fundamentals of the Bitcoin network.