But to the point: a U.S. state can't nationalize a private company. It simply lacks that power. The closest it can get is buying a private company, or creating a public agency or public-private partnership, all of which California has done before.
Or build its own competition. Quite a few califonia cities run their own utilities; Palo Alto started and ran its own phone company (sold to Pac Bell in the late 50s) and cable system (foolishly and destructively sold to crapcast in the '00s) but runs its own water, electricity, and gas system. Several counties run their own utility systems, often in cooperation.
However the high speed rail project suggests that this is not the time for California to enter into such projects. A century ago progressivism flourished, building water, road, and other crucial infrastructure that we still depend on. But the "revolution" of the late 70s and 80s cut away all the maintenance and support for further such projects in the name of ideology.
Eminent domain is in both the US constitution and the California state constitution. You usually have to provide compensation of course, but they made a list of exceptions that includes utilities: https://law.justia.com/constitution/california/article-i/sec...
The closest I can find is eminent domain which they can use to obtain privately owned land, but nothing that gives them the power to do what you're describing. Can you point me in the right direction?
As a last resort, eminent domain offering fair market enterprise value and an orderly transfer of control.
Is the idea that the secured creditors need the subsidy too?
NFL teams are franchises of the NFL, and owners of the other teams have to agree to ownership changes of each franchise. It's also not true that he suddenly "got wind of" anything, he'd been planning to move the team for 7-8 years and had very public spats with the city for years over it. He didn't tell the city ahead of time about the move because they had been at war with each other for many years.
NYC took control of the subways by capping fares which bankrupted the private operators.
This is commonly practiced in various city and county services: fire and police services, ambulance, public transit (virtually all extant bus and rail services began as privately-owned companies), school bussing, schools, childcare, parks and recreation, utilities (water, rubbish, electricity, gas, Internet, sewerage, ...), etc.
There's a long history of this, in California and elsewhere.
The Wikipedia article unfortunately doesn't dive much into the details of mechanism though it does point out numerous instances and issues.
That's how.
So no, that's not how.
However, lets say that California couldn't seize PG&Es assets directly (transmission lines, etc.) - that doesn't really matter as California can force PG&E's hand, given that they could easily put them out of business.
California is in control, it just doesn't have the political capital to do what's needed.