Can they really be replaced, though? There aren't an infinite number of people willing to do shitty internet janitorial work for free. You generally get two types of people to fill that role, those who are passionate about the subject and those who like having control.

The passionate ones are rare and special, they make a community good. They'll go away. The power-hungry ones might stick around. But they'll make the subs worse, and they're now serving at the whim of Reddit so they might not be so happy with that kind of "power" either. They could have so much more power - the power of the gods admins themselves - if they were to run their own instance on the Fediverse.

Reddit may find enough scabs to keep the lights on, but if this was really a cost-free solution to Reddit's problem they would have done it ages ago.