All change is mourned. This is nothing but market logic pursuing low costs, extracting work from gradients of wealth. In Hollywood the gradient is low compared to other “exotic” locations such as Toronto, Prague or Florida.
This exodus will remain until production costs in LA fall below the costs in other places, or LA can offer a measurable benefit compared to other locations.
Capitalism is a double edged sword - it allocates labor very efficiently, but when you are providing the labor, you don’t want to have that labor extracted from you too efficiently.